Fault Conditions

P1390

Random Misfire Detected. Catalyst Damaging. Fuel Level Low.







Fault symptoms
- CHECK ENGINE.
- Running unevenly and misfiring.

On-Board Diagnostics

Type of diagnosis:
- Continuous. But interrupted when fault criteria fulfilled and will not restart until next driving cycle.

Enable criteria
- 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.
- Engine started. Fuel level below 4 litres. Main relay voltage exceeding 10 V. Ignition discharge module combustion signals registered. The number of missing combustion signals is accumulated for each cylinder during 200 engine revolutions. The total number of accepted misfires during 200 engine revolutions is specified in a load and engine speed-dependent matrix.

Fault criteria
- Number of missing combustions exceeding number of accepted misfires. More than one cylinder has misfired.

Dependents
- P1312 and P1334.

System reaction to a fault
- Under high engine loads, closed loop will be blocked while misfiring occurs.

OK report
- Provided fault criteria are not fulfilled during the driving cycle, the OK report will made when the ignition is turned off and before the engine stops. Two other types of OK report can also be made:

Type 1: If a diagnostic trouble code has already been stored for the diagnosis and the same running conditions have occurred (coolant temperature above or below 71 °C, engine speed ±375 rpm and load ±10%).

Type 2: If there is no diagnostic trouble code stored for the diagnosis or the same running conditions have not occurred.

Fault handling: (For more information, )

- Type I.

Diagnostic help
If any other trouble codes have been generated, check whether fault diagnosis should start with them. Drive the car in the load and engine speed range shown by Freeze Frame. If the engine does not misfire, the trouble code was probably due to the fuel level being too low. Drive the car so that the catalyst diagnosis is performed. If necessary, change the catalytic converter.

If the engine misfires during test driving, conduct a general inspection of connectors and hoses, and then a thorough check of compression, ignition and fuel system.

Functions in the diagnostic tool related to the fault:
- Diagnostic status for the diagnosis.
- Misfire Cyl 1.
- Misfire Cyl 2.
- Misfire Cyl 3.
- Misfire Cyl 4.
- Multiplicative Adaptation, unit %.
- Additive adaptation, unit mg/c.
- Closed loop, unit %.
- Purge Adaptation, unit %.
- Air mass deviation from calculated, unit %.
- Activating misfire counter reset.
- Activating ignition triggers.
- Activating injector test.
- Activating pump test.

For more information,

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.

Proceed to Diagnostic Procedures Check Additional DTC's In the Trionic System - I