The symptoms shown in this incident are:
- Engine failure lamp (MIL) on
- On reading the fault codes in the engine control module (ECM) with the diagnostic tool, we see code P0420 is recorded (Catalyst system efficiency below threshold on bank 1).
The cause of this anomaly is due to a fault in the inlet sensor (sensor 1) of the catalytic converter.
The repair procedure for this fault is to measure the temperature with a thermometer at the inlet to the catalytic converter and to take another measurement at the outlet, and check that the inlet temperature is lower than the outlet temperature. If this is the case, directly replace the converter gas inlet sensor 1, because, as we say in this newsletter, it is a common fault and this solution is not always correct.
To assure yourself that the incident has been resolved, check that the exhaust gas system is operating correctly by means of a road test and the deletion of all the engine control module (ECM) fault codes.