P1172
Read the instructions below then
start the fault diagnostic procedure.
Symptom: Engine may stop after starting, uneven running and misfiring.
Short Term Fuel Trim. Min Value, Air/Fuel too Rich.
Fault symptoms
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Engine may stop after starting, uneven running and misfiring.
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Conditions
The following conditions apply for this DTC:
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Engine running and multiplicative adaptation has been performed during present driving cycle.
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Closed loop control below -25 % for more than 20 s.
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Diagnostic help
At some time, the engine's fuel requirement has been 25 % lower than that calculated by the control module on the basis of information from the mass air flow sensor.
Fault diagnosis first determines if the pressure sensor readings are approximately the same when the ignition is ON, as the mass air flow sensor is later compared with the intake air pressure. If the pressure sensors are OK but the mass air flow sensor reading is incorrect, first check for air leaks between the compressor and throttle and then change the mass air flow sensor.
If the mass air flow is OK, then the fuel supply must be checked, i.e. pressure, pressure response, pump flow and then the injectors.
Diagnostic tool functions related to this fault are:
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Short term fuel trim, in %.
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Multiplicative adaptation, in %
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Additive adaptation, in mg/c.
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Purge adaptation, in %.
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Airmass deviation from calculated, in %.
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See also the description of test values under ”Fault diagnosis, general” for more information.
Check the wiring
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Note
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Jiggle the leads and in-line connectors at various points and in different directions to detect any intermittent breaks or short circuits in the wiring. Observe the multimeter, test lamp or diagnostic tool while doing this.
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Diagnostic procedure
See diagnostic procedure P0172, see
.
