P1128

ADAPTATION MALFUNCTION





Fault Symptoms
CHECK ENGINE lamp (MIL) on.
Impaired driveability, hunting idle.
Any other diagnostic trouble codes, such as low fuel level, mass air flow sensor, misfiring.

Conditions.
P1123
Additive adaptation. Bank 1 is less than -0.485 ms.

P1124
Additive adaptation. Bank 1 is greater than +0.485 ms.

P1125
Additive adaptation. Bank 2 is less than -0.485 ms.

P1126
Additive adaptation. Bank 2 is greater than +0.485 ms.

P1127
Multiplicative adaptation. Bank 1 is less than -18.5%.

P1128
Multiplicative adaptation. Bank 1 is greater than +23%.

P1129
Multiplicative adaptation. Bank 2 is less than -18.5%.

P1130
Multiplicative adaptation. Bank 2 is greater than +23%.





Diagnostic Help.
If the adaptation malfunction has arisen as a result of low fuel level, this will be indicated by diagnostic trouble code P1585 also being generated.

An adaptation reading can be obtained with the ISAT scan tool.
- Select "READ FUNCTIONS".
- Select "ADDITIVE ADAPTION".
- Select "MULTIPL ADAPTION".

Current multiplicative adaptation is shown in % (±25%).

Current additive adaptation is shown in ms (±0.512).

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.





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.

Does the ISAT scan tool show additional diagnostic
trouble codes?
YES: Continue fault diagnosis as described for the appropriate diagnostic trouble code and then continue with point 5.
NO: Continue with point 2.

2. Check for air leakage

- Check that no air leakage occurs in the intake system after the mass air flow sensor. Carefully inspect all vacuum hoses and the crankcase breather hose.
- Check all systems that are connected to the intake system.
- Check that the EVAP canister purge valve does not leak under zero current conditions.

No leakage?
YES: Continue with point 3.
N0: Rectify the fault and continue with point 5.





3. Check the performance of the mass air flow sensor

- Connect the ISAT Scan Tool.
- Start the engine.
- Select "READ FUNCTIONS".
- Select "MASS AIR FLOW SENSOR".

Check that the ISAT scan tool shows the following air mass as a function of engine rpm:

^ idling speed: about 0.8 V.
^ at 2500 rpm (no load): about 1.2 V.

Slightly higher values will be obtained with a cold engine.

All readings OK?
YES: Continue with point 4.
NO: Change the mass air flow sensor and continue with point 5.





4. Other checks

- Check that:
^ the secondary air injection system is OK
^ fuel pressure is OK
^ no air leakage occurs in the exhaust system ahead of the oxygen sensors or at its mountings
^ no misfiring occurs.

All checks OK?
YES: Continue with point 5.
NO: Rectify the fault and continue with point 5.