P0422
Symptom: CHECK ENGINE lamp (MIL) on
Three way catalytic converter
Fault symptoms
CHECK ENGINE lamp (MIL) on
Conditions
The voltage amplitude from the rear heated oxygen sensor is compared with the voltage
amplitude from the front heated oxygen sensor and compared with a limit
value.
Three way catalytic converter heating
Vehicle speed ∼ 70 km/h for 3 minutes and 20 seconds.
Evaluation of the three way catalytic converter
Gentle acceleration from idling speed up to 2000-2500 rpm and then varying engine
load and speed between 2000 and 2500 rpm for a total time of 3 minutes and 20 seconds.
Diagnostic help
A temporary or permanent decrease in the capacity of the three way catalytic converter
may be caused by:
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leaded fuel or fuel with a sulphur
content.
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additives in the engine oil if oil consumption is abnormal.
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High exhaust temperature.
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Misfiring caused by low fuel level/low fuel pressure.
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Diagnostic procedure
1. Check the exhaust system
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Start the engine and run it at idling
speed.
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Check the exhaust system for leakage between the engine and the rear heated
oxygen sensor.
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Any leakage?
Rectify the fault. Continue with point 3.
Change the catalytic converter. Continue with point 2.
2. Check the fuel system
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Check the fuel pressure and fuel
pump delivery flow.
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Are the readings OK?
Continue with point 3.
Rectify the fault. Continue with point 3.
3. Final check
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Clear the diagnostic trouble
codes.
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