Monitoring Procedure

Following engine start-up, the IAT sensor output is monitored to determine whether indicated air temperature falls below 100°C after a period of time. Should the temperature not fall below 100°C, the range/performance failure judgement is made. The same judgement is made should a temperature drop of more than 20°C in 2 seconds be recorded. The DTC is stored if the failure judgement is made on two successive trips.

Sensor output is continuously monitored for high and low out of range values. If a sustained high, or low input to the ECM is seen (indicating a harness or connector fault), a high/low failure judgement is made. The relevant DTC is stored if the failure judgement is made on two successive trips.