heater LAND ROVER DISCOVERY 2002 User Guide

EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-13
The heated oxygen sensor is an integral part of the exhaust emission control system and is used in conjunction with
the catalytic converters and the engine management control unit to ensure that the air:fuel mixture ratio stays around
the stoichiometric point of
λ = 1, where the catalytic converters are most effective. Combinations of four (NAS only)
or two heated lambda sensors are used in the exhaust system dependent on market legislation.
The heated oxygen sensor is screwed into threaded mountings welded into the top of the front exhaust pipes at
suitable locations. They are used to detect the level of residual oxygen in the exhaust gas to provide an instantaneous
indication of whether combustion is complete. By positioning sensors in the stream of exhaust gases from each
separate bank of the exhaust manifold, the engine management system is better able to control the fuelling
requirements on each bank independently of the other, so allowing much closer control of the air:fuel ratio and
optimising catalytic converter efficiency.
Two pre-catalytic converter heated oxygen sensors are mounted in the front pipes for monitoring the oxygen content
of the exhaust gas. NAS models also have two additional post-catalytic converter heated oxygen sensors in the
exhaust front pipe.
CAUTION: HO2 sensors are easily damaged by dropping, over torquing, excessive heat or contamination.
Care must be taken not to damage the sensor housing or tip.
The oxygen sensors consist of a ceramic body (Galvanic cell) which is a practically pure oxygen-ion conductor made
from a mixed oxide of zirconium and yttrium. The ceramic is then coated with gas-permeable platinum, which when
heated to a sufficiently high temperature (
≥ 350° C) generates a voltage which is proportional to the oxygen content
in the exhaust gas stream.
The heated oxygen sensor is protected by an outer tube with a restricted flow opening to prevent the sensor's
ceramics from being cooled by low temperature exhaust gases at start up. The post-catalytic sensors have improved
signal quality, but a slower response rate.
The pre-catalytic and post-catalytic converter sensors are not interchangeable, and although it is possible to mount
them in transposed positions, their harness connections are of different gender and colour. It is important not to
confuse the sensor signal pins; the signal pins are gold plated, whilst the heater supply pins are tinned,
mixing them up will cause contamination and adversely affect system performance.
Each of the heated oxygen sensors have a four pin connector with the following wiring details:
lSensor signal ground (grey wire – connects to engine management ECM)
lSensor signal (black wire – connects to engine management ECM)
lHeater drive (white wire – connects to engine management ECM)
lHeater supply (white wire – connects to fuse 2, underbonnet fuse box)
The ECM connector pins for exhaust emission control are listed in the following table:
ECM Connector 2 (C635) pin-out details for exhaust emission control system
Pin Number Function Signal Type Control
2-01 Post-cat sensor heater (RH) - NAS only Output, Drive PWM, 12 - 0V
2-07 Post-cat sensor heater (LH) - NAS only Output, Drive PWM, 12 - 0V
2-08 Post-cat sensor (RH) - NAS only Ground, Signal 0V
2-09 Pre-cat sensor (LH) Ground, Signal 0V
2-10 Pre-cat sensor (RH) Ground, Signal 0V
2-11 Post-cat sensor (LH) - NAS only Ground, Signal 0V
2-13 Pre-cat sensor heater (RH) Output, Drive PWM, 12 - 0V
2-14 Post-cat sensor (RH) - NAS only Input, Signal Analogue, 0 - 1V
2-15 Pre-cat sensor (LH) Input, Signal Analogue, 0 - 1V
2-16 Pre-cat sensor (RH) Input, Signal Analogue, 0 - 1V
2-17 Post-cat sensor (LH) - NAS only Input, Signal Analogue, 0 - 1V
2-19 Pre-cat sensor heater (LH) Output, Drive PWM, 12 - 0V

EMISSION CONTROL - V8
17-2-34 DESCRIPTION AND OPERATION
Exhaust emission control operation
The oxygen content of the exhaust gas is monitored by heated oxygen sensors using either a four sensor (NAS only)
or two sensor setup, dependent on market destination and legislative requirements. Signals from the heated oxygen
sensors are input to the engine management ECM which correspond to the level of oxygen detected in the exhaust
gas. From ECM analysis of the data, necessary changes to the air:fuel mixture and ignition timing can be made to
bring the emission levels back within acceptable limits under all operating conditions.
Changes to the air:fuel ratio are needed when the engine is operating under particular conditions such as cold starting,
idle, cruise, full throttle or altitude. In order to maintain an optimum air:fuel ratio for differing conditions, the engine
management control system uses sensors to determine data which enable it to select the ideal ratio by increasing or
decreasing the air to fuel ratio. Improved fuel economy can be arranged by increasing the quantity of air to fuel to
create a lean mixture during part-throttle conditions, however lean running conditions are not employed on closed loop
systems where the maximum is
λ = 1. Improved performance can be established by supplying a higher proportion of
fuel to create a rich mixture during idle and full-throttle operation. Rich running at wide open throttle (WOT) for
performance and at high load conditions helps to keep the exhaust temperature down to protect the catalyst and
exhaust valves.
The voltage of the heated oxygen sensors at
λ = 1 is between 450 and 500 mV. The voltage decreases to 100 to 500
mV if there is an increase in oxygen content (
λ > 1) indicating a lean mixture. The voltage increases to 500 to 1000
mV if there is a decrease in oxygen content (
λ < 1), signifying a rich mixture.
The heated oxygen sensor needs to operate at high temperatures in order to function correctly (
≥ 350° C). To achieve
this the sensors are fitted with heater elements which are controlled by a pulse width modulated (PWM) signal from
the engine management ECM. The heater element warms the sensor's ceramic layer from the inside so that the
sensor is hot enough for operation. The heater elements are supplied with current immediately following engine start
and are ready for closed loop control within about 20 to 30 seconds (longer at cold ambient temperatures less than
0
°C (32°F)). Heating is also necessary during low load conditions when the temperature of the exhaust gases is
insufficient to maintain the required sensor temperatures. The maximum tip temperature is 930
° C.
A non-functioning heater element will delay the sensor's readiness for closed loop control and influences emissions.
A diagnostic routine is utilised to measure both sensor heater current and the heater supply voltage so its resistance
can be calculated. The function is active once per drive cycle, as long as the heater has been switched on for a pre-
defined period and the current has stabilised. The PWM duty cycle is carefully controlled to prevent thermal shock to
cold sensors.
The heated oxygen sensors age with mileage, causing an increase in the response time to switch from rich to lean
and lean to rich. This increase in response time influences the closed loop control and leads to progressively
increased emissions. The response time of the pre-catalytic converter sensors are monitored by measuring the period
of rich to lean and lean to rich switching. The ECM monitors the switching time, and if the threshold period is exceeded
(200 milliseconds), the fault will be detected and stored in the ECM as a fault code (the MIL light will be illuminated
on NAS vehicles). NAS vehicle engine calibration uses downstream sensors to compensate for aged upstream
sensors, thereby maintaining low emissions.
Diagnosis of electrical faults is continuously monitored for both the pre-catalytic converter sensors and the post-
catalytic converter sensors (NAS only). This is achieved by checking the signal against maximum and minimum
threshold for open and short circuit conditions. For NAS vehicles, should the pre- and post-catalytic converters be
inadvertently transposed, the lambda signals will go to maximum but opposite extremes and the system will
automatically revert to open loop fuelling. The additional sensors for NAS vehicles provide mandatory monitoring of
the catalyst conversion efficiency and long term fuelling adaptations.
Note that some markets do not legislate for closed loop fuelling control and in this instance no heated oxygen
sensors will be fitted to the exhaust system.

EMISSION CONTROL - V8
17-2-36 DESCRIPTION AND OPERATION
Exhaust Emission System Diagnostics
The engine management ECM contains an on-board diagnostics (OBD) system which performs a number of
diagnostic routines for detecting problems associated with the closed loop emission control system. The diagnostic
unit monitors ECM commands and system responses and also checks the individual sensor signals for plausibility,
these include:
lLambda ratio outside of operating band
lLambda heater diagnostic
lLambda period diagnostic
lPost-catalytic converter lambda adaptation diagnostic (NAS only)
lCatalyst monitoring diagnostic
Lambda ratio outside operating band
The system checks to ensure that the system is operating in a defined range around the stoichiometric point. If the
system determines that the upper or lower limits for the air:fuel ratio are being exceeded, the error is stored as a fault
code in the ECM diagnostic memory (the MIL light is illuminated on NAS vehicles).
Lambda heater diagnostic
The system determines the heater current and supply voltage so that the heater's resistance can be calculated. After
the engine has been started, the system waits for the heated oxygen sensors to warm up, then calculates the
resistance from the voltage and current measurements. If the value is found to be outside of the upper or lower
threshold values, then the fault is processed (the MIL light is illuminated on NAS vehicles).
Lambda period diagnostic
The pre-catalytic converter sensors are monitored. As the sensors age, the rich to lean and the lean to rich switching
delays increase, leading to increased emissions if the lambda control becomes inaccurate. If the switching period
exceeds a defined limit, the sensor fault is stored in the ECM diagnostic memory (the MIL light is illuminated on NAS
vehicles).
Post-catalytic converter lambda adaptation diagnostic (NAS only)
On NAS vehicles the ageing effects of the pre-catalytic converter sensors are compensated for by an adaptive value
derived from the post-catalytic converter sensors. This is a long term adaption which only changes slowly. For a rich
compensation the additive value is added to the rich delay time. For a lean compensation, the adaptive value is added
to the lean delay time. The adaptive time is monitored against a defined limit, and if the limit is exceeded, the fault is
stored in the ECM's diagnostic memory and the MIL light is illuminated on the instrument pack.
Catalyst monitoring diagnostic
On NAS specification vehicles the catalysts are monitored both individually and simultaneously for emission pollutant
conversion efficiency. The conversion efficiency of a catalyst is monitored by measuring the oxygen storage, since
there is a direct relationship between these two factors. The closed loop lambda control fuelling oscillations produce
pulses of oxygen upstream of the catalyst, as the catalyst efficiency deteriorates its ability to store oxygen is
decreased. The amplitudes of the signals from the pre-catalytic and post-catalytic converter heated oxygen sensors
are compared. As the oxygen storage decreases, the post-catalytic converter sensor begins to follow the oscillations
of the pre-catalytic converter heated oxygen sensors. Under steady state conditions the amplitude ratio is monitored
in different speed / load sites. There are three monitoring areas, and if the amplitude ratio exceeds a threshold in all
three areas the catalyst conversion limit is exceeded; the catalyst fault is stored in the diagnostic memory and the MIL
light is illuminated on the instrument pack. There is a reduced threshold value for both catalysts monitored as a pair.
In either case, a defective catalyst requires replacement of the downpipe assembly.

EMISSION CONTROL - V8
REPAIRS 17-2-51
Air Manifold - LH - Secondary Air
Injection (SAI)
$% 17.25.17
Remove
1.Remove SAI control valve.

+ EMISSION CONTROL - V8,
REPAIRS, Control Valve - Secondary Air
Injection (SAI).
2.Loosen 2 union nuts securing air manifold to
cylinder head adaptors.
3.Remove 2 nuts securing air manifold bracket to
inlet manifold.
4.Remove air manifold.
Refit
1.Clean air manifold and cylinder head adaptors.
2.Fit air manifold and start union nuts.
3.Fit nuts securing air manifold to inlet manifold.
4.Tighten air manifold unions to 25 Nm.
5.Fit SAI control valve.

+ EMISSION CONTROL - V8,
REPAIRS, Control Valve - Secondary Air
Injection (SAI).
Air Manifold - RH - Secondary Air
Injection (SAI)
$% 17.25.18
Remove
1.Remove SAI control valve.

+ EMISSION CONTROL - V8,
REPAIRS, Control Valve - Secondary Air
Injection (SAI).
2.Remove heater feed pipe.

+ HEATING AND VENTILATION,
REPAIRS, Pipe - Heater - Feed.
3.Loosen 2 union nuts securing air manifold to
cylinder head adaptors.
4.Remove nut securing air manifold bracket to
inlet manifold.
5.Remove air manifold.
Refit
1.Clean air manifold and cylinder head adaptors.
2.Fit air manifold and start union nuts.
3.Fit nut securing air manifold to inlet manifold.
4.Tighten air manifold unions to 25 Nm.
5.Fit heater feed pipe.

+ HEATING AND VENTILATION,
REPAIRS, Pipe - Heater - Feed.
6.Fit SAI control valve.

+ EMISSION CONTROL - V8,
REPAIRS, Control Valve - Secondary Air
Injection (SAI).
M17 0234
4
3
2
2
M17 0223
43
3
5

EMISSION CONTROL - V8
REPAIRS 17-2-53
8.Remove 2 nuts securing air injection pipe to air
intake plenum.
9.Release pipe from clip on rear of air intake
plenum.
10.Release 3 clips securing harness to engine bay
bulkhead.
11.Position container to collect any coolant
spillage.
12.Release clips securing heater hoses to heater.
13.Release hoses from heater.
14.With assistance, manoeuvre air injection pipe
from engine bay.Refit
1.With assistance, manoeuvre air injection pipe
into engine bay and secure onto clip at rear of
air intake plenum.
2.Connect heater hoses to heater and secure
with clips.
3.Reposition harness along engine bay bulkhead
and secure with clips.
4.Fit and tighten nuts securing air injection pipe to
air intake plenum.
5.Connect multiplug to SAI vacuum solenoid.
6.Connect air pump hose to air injection pipe and
secure with clip.
7.Connect LH and RH SAI control valve hoses to
air injection pipe and secure with clips.
8.Remove container.
9.Top up engine coolant.

+ MAINTENANCE, PROCEDURES,
Cooling system.
M17 0231
M17 0232
M17 0233

ENGINE MANAGEMENT SYSTEM - TD5
DESCRIPTION AND OPERATION 18-1-31
The purpose of the glow plugs is:
lAssist cold engine start.
lReduce exhaust emissions at low engine load/speed.
The main part of the glow plug is a tubular heating element that protrudes into the combustion chamber of the engine.
The heating element contains a spiral filament that is encased in magnesium oxide powder. At the tip of the tubular
heating element is the heater coil. Behind the heater coil and connected in series is a control coil. The control coil
regulates the heater coil to ensure that it does not overheat and cause a possible failure. The glow plug circuit has its
own control relay located in the engine compartment fuse box.
Pre-heat is the length of time the glow plugs operate prior to engine cranking. The ECM controls the pre-heat time of
the glow plugs based on battery voltage and coolant temperature information via the glow plug relay.
Post-heat is the length of time the glow plugs operate after the engine starts. The ECM controls the post-heat time
based on ECT information. If the ECT fails the ECM will operate pre/post-heat time strategies with default values from
its memory. The engine will be difficult to start.
Input/Output
The glow plugs receive voltage from the glow plug relay that is controlled by the ECM. The ECM provides the earth
path for the relay coil closing the relay contacts and supplying the glow plugs with battery voltage. The supply voltage
heats the coils to approximately 1000
°C (1832 °F). The glow plug circuit is wired in parallel, the body of each glow
plug is screwed directly into the engine block which provides each glow plug with an earth path.
The glow plugs can fail in the following ways:
lHeater coil open circuit.
lControl coil open circuit.
lPoor earth quality.
lShort circuit to vehicle supply.
lShort circuit to vehicle earth.
lWiring loom fault.
lRelay windings open circuit.
lIncorrect relay fitted.
In the event of a glow plug failure any of the following symptoms may be observed:
lDifficult starting.
lExcessive smoke emissions after engine start.

ENGINE MANAGEMENT SYSTEM - V8
18-2-8 DESCRIPTION AND OPERATION
Input/Output
The ECM has various sensors fitted to the engine to allow it to monitor engine condition. The ECM processes these
signals and decides what actions to carry out to maintain optimum engine operation by comparing the information
from these signals to mapped data within its memory.
Connector 1 (C0634): This connector contains 9 pins and is used primarily for ECM power input and earth. The ECM
requires a permanent battery supply, if this permanent feed is lost i.e. the battery discharges or is disconnected the
ECM will lose its adapted values and its Diagnostic Trouble Codes (DTC). These adapted values are a vital part of
the engine management's rolling adaptive strategy. Without an adaptive strategy, driveability, performance, emission
control, and fuel consumption are adversely affected. The ECM can be damaged by high voltage inputs, so care must
be taken when removing and replacing the ECM.
Pin out details connector C0634
Connector 2 (C0635): This connector contains 24 pins and is primarily used for Heated Oxygen Sensors (HO
2S)
control and earth. The HO
2S sensors require a heater circuit to assist in heating the tip of the sensors to enable closed
loop fuelling to be implemented quickly after cold starting.
Pin out details connector C0635
Pin No. Function Signal type Reading
1 Ignition position II Input 12 V
2 Not used - -
3 Not used - -
4 Chassis earth Earth 0V
5 Fuel injectors earth Earth 0V
6 Power stage earth Earth 0V
7 Permanent battery supply Input battery supply 12V
8 Switched relay positive Input switched 0-12V
9 Not used - -
Pin No. Function Signal type Reading
1HO
2S heater RH bank - downstream Output PWM 12-0V
2 Not used - -
3 Not used - -
4 Not used - -
5 Thermostat monitoring sensor Earth 0V
6 Not used - -
7HO
2S heater LH bank - downstream Output PWM 12-0V
8HO
2S sensor RH bank - downstream Earth/ Signal 0V
9HO
2S sensor LH bank - upstream Earth/ Signal 0V
10 HO
2S sensor RH bank - upstream Earth/ Signal 0V
11 HO
2S sensor LH bank - downstream Earth/ Signal 0V
12 Not used - -
13 HO
2S heater RH bank - upstream Output PWM 12-0V
14 HO
2S sensor RH bank - downstream Input/ Signal Analogue 0-5V
15 HO
2S sensor LH bank - upstream Input/ Signal Analogue 0-5V
16 HO
2S sensor RH bank - upstream Input/ Signal Analogue 0-5V
17 HO
2S sensor LH bank - downstream Input/ Signal Analogue 0-5V
18 Fuel pump relay Output Switch to earth
19 HO
2S heater LH bank - upstream Output PWM 12-0V
20 Not used - -
21 Thermostat monitoring sensor Signal Analogue 0-5V
22 Not used - -
23 Main relay Output Switch to earth
24 EVAP system leak detection pump motor (NAS
vehicles with positive pressure type, EVAP system
leak detection capability only)Output Switch to earth

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-11
31 Positive pressure type EVAP system heater
(02MY vehicles only)Output, drive Switched earth
32 Diagnostic connector K-line Bi-directional Serial 0-12V
33 Immobiliser serial W link Input, signal Serial 0-12V
34 Rough road signal Input, signal PWM 0-12V
35 Not used - -
36 CAN data bus 'high line' Bi-directional 5-2.5V
37 CAN data bus 'low line' Bi-directional 0-2.5V
38 ATC stand by Input, signal Active low
39 Not used - -
40 Not used - - Pin No. Function Signal type Reading

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-27
The HO2S uses zirconium contained in a galvanic cell surrounded by a gas permeable ceramic, this produces an
output voltage proportional to the ratio difference between the oxygen in the exhaust gases and to the ambient
oxygen.
The HO
2S operates at approximately 350 °C (662 °F). To achieve this temperature the HO2S incorporate a heating
element which is controlled by a PWM signal from the ECM. The elements are activated immediately after engine
starts and also under low engine load conditions when the exhaust gas temperature is insufficient to maintain the
required HO
2S temperature. If the heater fails, the ECM will not allow closed loop fuelling to be implemented until the
sensor has achieved the required temperature.
This value equates to an HO
2S output of 450 to 500 mV. A richer mixture can be shown as λ = 0.97, this pushes the
HO
2S output voltage towards 1000 mV. A leaner mixture can be shown as λ = 1.10, this pushes the HO2S output
voltage towards 100 mV.
From cold start, the ECM runs an open loop fuelling strategy. The ECM keeps this strategy in place until the HO
2S is
at a working temperature of 350
°C (662 °F). At this point the ECM starts to receive HO2S information and it can then
switch into closed loop fuelling as part of its adaptive strategy. The maximum working temperature of the tip of the
HO
2S is 930 °C (1706 °F), temperatures above this will damage the sensor.
HO
2S age with use, this increases their response time to switch from rich to lean and from lean to rich. This can lead
to increased exhaust emissions over a period of time. The switching time of the upstream sensors are monitored by
the ECM. If a pre-determined threshold is exceeded, a failure is detected and the MIL illuminated.

+ EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Exhaust emission control system.
Input/Output
The upstream and downstream HO
2S are colour coded to prevent incorrect fitting. The tips of the upstream sensors
are physically different to the tips of the downstream sensors.
The HO
2S are colour coded as follows:
lUpstream sensors (both banks) - orange.
lDownstream sensors (both banks) - grey.
The four HO
2S have a direct battery supply to the heater via fuse 2 located in the engine compartment fuse box.
The heater is driven by the ECM providing an earth path for the circuit as follows:
lUpstream LH bank via pin 19 of connector C0635 of the ECM.
lUpstream RH bank via pin 13 of connector C0635 of the ECM.
lDownstream LH bank via pin 7 of connector C0635 of the ECM.
lDownstream RH bank via pin 1 of connector C0635 of the ECM.
The HO
2S output signal is measured by the ECM as follows:
lUpstream LH bank via pin 15 of connector C0635 of the ECM.
lUpstream RH bank via pin 16 of connector C0635 of the ECM.
lDownstream LH bank via pin 17 of connector C0635 of the ECM.
lDownstream RH bank via pin 14 of connector C0635 of the ECM.
The HO
2S earth path for the signal is supplied by the ECM as follows:
lUpstream LH bank via pin 9 of connector C0635 of the ECM.
lUpstream RH bank via pin 10 of connector C0635 of the ECM.
lDownstream LH bank via pin 11 of connector C0635 of the ECM.
lDownstream RH bank via pin 8 of connector C0635 of the ECM.
The HO
2S voltage is difficult to measure using a multimeter, the output can be monitored using TestBook. A rich
mixture would read 500 to 1000 mV, a weak mixture would read 100 mV to 500 mV, the reading should switch from
rich to weak. The open loop default voltage is 450 mV, this is used by the ECM to set the air/ fuel ratio until the tip of
the HO
2S reaches operating temperature.

ENGINE MANAGEMENT SYSTEM - V8
18-2-28 DESCRIPTION AND OPERATION
The HO2S can fail the following ways or supply incorrect signal:
lSensor open circuit.
lShort circuit to vehicle supply.
lShort circuit to vehicle earth.
lSensor disconnected.
lStoichiometric ratio outside the correct operating band.
lContamination from leaded fuel.
lAir leak into the exhaust system.
lWiring loom damage.
lSensors fitted incorrectly or cross wired.
In the event of a HO
2S signal failure any of the following symptoms may be observed:
lDefault to open loop fuelling on defective bank.
lIf the sensors are crossed over (LH bank to RH bank), the engine will run normally after initial start up, but
performance will become progressively worse as the sensors go towards maximum rich for one bank of cylinders
and maximum lean for the other. The ECM will eventually default into open loop fuelling.
lHigh CO reading.
lExcess emissions.
lStrong hydrogen sulphide (H
2S) smell until the ECM defaults to open loop fuelling. .
lMIL illuminated (NAS market only).
A number of diagnostic tests are performed by the ECM with regards to the HO
2sensors:
lHO
2 sensor and system diagnostics
lHO
2 sensor heater diagnostics
lHO
2 sensor switching period (ageing) diagnostics
lRear HO
2 sensor adaption diagnostic (NAS only)
lCatalyst monitoring diagnostic
For further details of the heated oxygen sensors and exhaust emission control, refer to the V8 Emission Control
section of this manual.

+ EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Exhaust emission control system.
Should a malfunction of the component occur the following fault codes may be evident and can be retrieved by
TestBook:
P Code J2012 Description Land Rover Description
P1129 O
2 sensors swapped bank to bank (sensor 1) Front sensors transposed
P0130 O
2 sensor circuit malfunction (bank 1, sensor 1) Front sensor LH bank stoichiometric ratio outside
operating band
P0132 O
2 sensor circuit high voltage (bank 1, sensor 1) Front sensor LH bank short circuit to battery supply
P0134 O
2 sensor circuit no activity detected (bank 1,
sensor 1)Front sensor LH bank open circuit
P0150 O
2 sensor circuit malfunction (bank 2, sensor 1) Front sensor RH bank stoichiometric ratio outside
operating band
P0152 O
2 sensor circuit high voltage (bank 2, sensor 1) Front sensor RH bank short circuit to battery supply
P0154 O
2 sensor circuit no activity detected (bank 2,
sensor 1)Front sensor RH bank open circuit
P0136 O
2 sensor circuit malfunction (bank 1, sensor 2) Rear sensor LH bank stoichiometric ratio outside
operating band (NAS only)
P0137 O
2 sensor circuit low voltage (bank 1, sensor 2) Rear sensor LH bank short circuit to earth (NAS only)
P0138 O
2 sensor circuit high voltage (bank 1, sensor 2) Rear sensor LH bank short circuit to battery supply
(NAS only)
P0140 O
2 sensor circuit no activity detected (bank 1,
sensor 2)Rear sensor LH bank open circuit (NAS only)
P0156 O
2 sensor circuit malfunction (bank 2, sensor 2) Rear sensor RH bank stoichiometric ratio outside
operating band (NAS only)
P0157 O
2 sensor circuit low voltage (bank 2, sensor 2) Rear sensor RH bank short circuit to earth (NAS only)