P1492
Symptom: Market US/CA: CHECK ENGINE.
Possible faulty readings on the fuel gauge in the MIU.
EVAP Tank pressure sensor. Value too low in depressurized state at the same time as the fuel level sensor diagnosis has reported a fault.
Fault symptoms
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Market US/CA: CHECK ENGINE.
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Possible faulty readings on the fuel gauge in the MIU.
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On-Board Diagnostics
Type of diagnosis:
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Once per driving cycle. Interrupted when fault criteria fulfilled or OK reported. Restarts next driving cycle.
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Enable criteria:
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General condition for this diagnostic trouble code: Atmospheric pressure must exceed 72 kPa as well as coolant and intake air temperature must exceed -7°C.
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Accepted transition diagnosis of oxygen sensor 1. Purge active. Idling. Max. one change in status of brake light switch. Purge adaptation higher than -7%. Car stationary for 8 s.
The diagnosis will start once the above conditions have been fulfilled. If the diagnosis is interrupted then the speed must exceed 0 on one occasion before it is allowed to restart.
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Fault criteria:
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Tank pressure below 1.8 kPa for 6.5 s.
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Generating diagnostic trouble codes:
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Fuel Level, plausibility diagnosis:
Because the fuel level is used as enable critera in certain diagnoses, the control module must know that the fuel level value is plausible. The way it works is that the Trionic receives a bus message ”Fuel level XX litres" from the MIU. During driving the Trionic observes the value and as the car is driven, fuel is consumed. The Trionic makes sure the fuel level value drops. In the Trionic a number of important filtrations are carried out to avoid faults caused by, for instance, splashing fuel in the tank, starting uphill. The fuel level diagnosis can be called a support diagnosis as it does not generate a DTC, but if for instance the EVAP tank pressure sensor diagnosis has reported performance problems (e.g. low value) in the EVAP tank pressure sensor then DTC P1452 is normally generated. If on the other hand the tank pressure sensor diagnosis has reported the same fault and the fuel level diagnosis has simultaneously reported a fault the DTC
P1492
is generated instead.
Diagnostic Trouble Codes are generated when the fault criteria are fulfilled and the dependants are OK.
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Dependents:
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P0444, P0445, P0501, P0502, P0506, P0507, P1444, P1445, P1576 and P1577.
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System reaction to a fault:
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Integrity diagnosis of purge system blocked. Purge and fuel adaptation blocked.
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OK report:
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Diagnoses for P1451, P1452 and P1453 performed once and fault criteria not fulfilled. Fault criteria for P0452 or P0453 not fulfilled.
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Fault handling:
(For more information, see
.)
Diagnostic help
Fault diagnosis concerns checking tank pressure equalization to atmosphere or electrical fault in connecting leads or in the sensor.
Functions in the diagnostic tool related to the fault:
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Diagnostic status for the diagnosis.
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Pressure sensor value, unit kPa. The value should be about 0 kPa when the filler cap is removed.
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For more information, see
.
Checking the wiring
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short circuits. Observe the multimeter, diagnostic tool or test lamp during the check.
