P0131
FRONT HEATED OXYGEN SENSOR, CYLINDER BANK 1 (REAR BANK)
Fault Symptoms
CHECK ENGINE lamp (MIL) on.
Any other diagnostic trouble codes, such as misfiring, closed loop, adaptation.
Conditions.
For all diagnostic trouble codes, preheating shall have been active for more than 200 seconds after starting.
The closed loop system should be active.
P0130
Sensor voltage 0.06-0.4 V and sensor 2 exceeds 0.5 V for longer than 20 seconds.
P0131
Sensor voltage less than -0.15 V for longer than 0.2 seconds.
P0132
Sensor voltage exceeds 1.1 V for longer than 0.2 seconds.
P0133
^ Engine speed 1400-2640 rpm.
^ Partial load 1.45-3.0 ms.
^ Oxygen sensor frequency below 2 Hz.
^ Exhaust temperature higher than 352°C.
P0134
^ Sensor voltage 0.4-0.6 V for longer than 3.5 seconds.
^ Sensor voltage for sensors 1 and 2 higher than 0.2 V on fuel shut-off for longer than 1 second.
Diagnostic Help.
The performance of the oxygen sensor can be ascertained with an ISAT scan tool.
- Select "READ FUNCTIONS"
- Select "OXY SENSOR BANK 1"
- Read "OXY SENSOR FRONT"
With the closed loop system active the ISAT scan tool reading should swing between 0.1 and 0.9 V.
Check The Wiring.
Intermittent faults may occur as a result of temporary short circuits and breaks in the wiring. Jiggle the wiring at several points and in different directions to ascertain whether the wiring harness, including any connectors, is causing the trouble. Observe the multimeter, ISAT scan tool or test lamp while doing this.
NOTE: If the reference ground or voltage of any of the oxygen sensors is shorted to battery positive (B+) in the wiring harness or in any of the oxygen sensors, all the following diagnostic trouble codes will usually be generated: P0132, P0152, P0138 and P0158.
If the reference ground of the oxygen sensors via pin 46 is shorted to battery negative (B-) in the wiring harness or in any of the oxygen sensors, all the following diagnostic trouble codes will usually be generated: P0131, P0151, P0137 and P0157.
If the preheating element of an oxygen sensor develops a fault, the performance of the sensor will deteriorate. This will be particularly noticeable at idling speed. A diagnostic trouble code indicating that the sensor is unserviceable could then be generated. Diagnostic trouble codes that are generated indicate that the fault is an open circuit. If diagnostic trouble codes are generated for both open circuit and preheating, the trouble code for preheating should be attended to first.
Following this, the performance of the oxygen sensor should be checked.
Diagnostic Procedure.
1. Check other diagnostic trouble codes in the Motronic system
- Use an ISAT scan tool to obtain readouts of all diagnostic trouble codes.
Any other diagnostic trouble codes ?
YES: Diagnostic trouble code P1115.
Carry out fault diagnosis and a final check as described for diagnostic trouble code P1115.
YES: Diagnostic trouble code P0132 and any of the following diagnostic trouble codes:
P0152, P0138 or P0158.
Continue with point 2.
YES: Diagnostic trouble code P0131 and any of the following diagnostic trouble codes:
P0151, P0137 or P0157.
Continue with point 3.
NO: Continue with point 4.
2. Check shorting to battery positive (B+)
One of the leads of the oxygen sensors connected to pin 18, 19, 76, 77 or 46 is shorted to battery positive (B+) in the wiring harness or in one of the oxygen sensors.
- Check the insulation of the oxygen sensors.
- Unplug the four 4-pin oxygen sensor connectors.
- Check the resistance of the sensors:
^ pins 1 to 3: OL (infinite resistance)
^ pins 1 to 4: OL (infinite resistance)
Are all readings OK?
YES: Check the relevant lead connected to control module pin 18, 19, 76, 77 or 46 and repair or replace it if necessary. Then continue with point 6.
NO: Change the relevant oxygen sensor. Then continue with point 6.
3. Check shorting to battery negative (B-)
The lead connected to pin 46 of the control module is shorted to battery negative (B-) in the wiring harness or in one of the oxygen sensors.
- Check the insulation of the oxygen sensors.
- Unplug the four 4-pin oxygen sensor connectors.
- Check the resistance of the sensors:
^ pin 3 to B-: OL (infinite resistance)
^ pin 4 to B-: OL (infinite resistance)
Are all readings OK?
YES: Check the lead connected to pin 46 of the control module for shorting to ground and repair or replace it if necessary. Then continue with point 6.
NO: Change the relevant oxygen sensor. Then continue with point 6.
4. Check the control module's sensor ground
- Unplug the 4-pin oxygen sensor connectors.
- Turn the ignition switch to the ON position.
- Take a voltage reading on the relevant connector between:
^ pin 3 and B-: 0.7 V.
Is the reading obtained OK?
YES: Continue with point 5.
NO: Check the lead in question and repair or replace it if necessary. Then continue with point 6.
5. Check the control module's sensor input
- Connect the ISAT Scan Tool.
- Turn the ignition switch to the ON position.
- Select "READ FUNCTIONS"
- Select "OXY SENSOR BANK 1"
- Read "OXY SENSOR FRONT"
The ISAT scan tool should show a reading of about 0.45 V.
- Connect a jumper lead between pins 3 and 4 in the oxygen sensor connector.
The ISAT scan tool should show a reading of about 0 V.
Are all readings OK?
YES: Change the oxygen sensor. Then continue with point 6.
NO: Check the leads in question and repair or replace them as necessary. Then continue with point 6.
6. Final check
- Clear the diagnostic trouble code.
- Implementation of driving cycle:
^ Drive the car at varying engine loads and rpm for 5 minutes.
- Evaluation of driving cycle:
^ Connect the ISAT Scan Tool.
^ Select "ON OFF"
^ Select "DIAGNOSTIC STATUS"
^ Select "OXY SENSOR BANK 1"
^ Read "OXY SENSOR FRONT"
Does the ISAT scan tool read "NOT READY"?
Repeat the driving cycle.
Check whether the diagnostic trouble code has recurred.
If the diagnostic trouble code has recurred, continue as described at "Before Replacing a Control Module". Component Tests and General Diagnostics
If the diagnostic trouble code has not recurred, the steps taken to rectify the fault were correct.