P1123,P1124, P1127, P1128
Symptom: CHECK ENGINE LAMP (MIL) on. Poorer driveability, hunting idle speed.
Possibly also other diagnostic trouble codes, e.g. low fuel level, mass air flow sensor,
misfiring.
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P1123
,
P1124
,
P1127
,
P1128
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Adaptation malfunction
Fault symptoms
CHECK ENGINE LAMP (MIL) on. Poorer driveability, hunting idle speed.
Possibly also other diagnostic trouble codes, e.g. low fuel level, mass air flow sensor,
misfiring.
Conditions
P1123 Additive adaptation < 0.5 ms.
P1124 Additive adaptation > 0.5 ms.
P1127 Multiplicative adaptation < -24%%.
P1128 Multiplicative adaptation > 22%%.
Diagnostic help
An adaptation reading can be obtained with the ISAT scan tool.
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Select "READ
FUNCTIONS".
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-
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Select "ADDITIVE ADAPTION".
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-
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Select "MULTIPL ADAPTION".
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Current multiplicative adaptation is show as a percentage (±25 %%).
Current additive adaptation is show in ms (±0.512 ms).
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
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Use an ISAT scan tool to obtain
readouts of all diagnostic trouble codes.
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Does the ISAT scan tool show additional diagnostic trouble codes?
Continue fault diagnosis as described for the relevant diagnostic trouble code.
Continue with point 5.
Continue with point 2.
2. Check for air leakage in the intake system
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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. Inspect the two O-rings in the intake silencer.
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-
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Check all systems that are connected to the intake system.
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Check that the EVAP canister purge valve does not leak under zero current
conditions.
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Is the intake system OK?
Continue with point 3.
Rectify the fault. Continue with point 5.
3. Check the performance of the mass air flow
sensor
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Connect the ISAT Scan
Tool.
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Turn off the A/C and all electrical equipment.
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Select "READ FUNCTIONS".
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Select "MASS AIR FLOW SENSOR".
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Check that the ISAT scan tool shows the following air mass as a function of
engine rpm:
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•
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idling speed . . . . . . . . . . . . . . . . . .
. . . . . . about 1.0 V
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•
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at 2500 rpm (no load) . . . . . . . . . .
. . . . about 1.5 V
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Slightly higher values will be obtained with a cold engine.
Are all readings OK?
Continue with point 4.
Change the mass air flow sensor. Continue with point 5.
4. Other checks
Checks OK?
Continue with point 5.
Rectify the fault. Continue with point 5.
5. Final check
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Connect the ISAT Scan
Tool.
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Start the engine and run it at idling speed until the temperature of the coolant has
attained 60°C (140°F).
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-
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Switch off the engine, restart it and run it at idling speed until the EVAP canister
purge valve stops working (about 90 seconds).
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-
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Read "MULTIPL. ADAPTION" during the time the EVAP canister purge valve is
not working (about 80 seconds).
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Does the ISAT scan tool show >+15%% or <-15%%?
Continue as described in
.
The steps taken to rectify the fault were correct.
