Range / Performance Failure

Range / performance failure
The monitor checks that the fuel rail temperature sensor signal is not stuck within normal operating range. It checks that the signal has varied by a calibrated amount before the coolant temperature signal has increased by 40 °C and twenty minutes of engine running has elapsed. Maximum and minimum values of fuel rail temperature and coolant temperature are continually calculated. If the difference between the fuel rail temp max and min values is greater than the calibrated threshold then normal judgement is made. For failure judgement, the monitor can only flag a failure if a cold start is detected. A cold start is detected when the difference between the intake air and coolant temp is less than a calibrated value, and the coolant temp is less than a second calibrated value. If a cold start has been detected, the difference between the max and min coolant temp values is greater than 40 °C, 20 minutes of engine run time has elapsed and the difference between maximum and minimum fuel rail temperatures is less than the normal threshold, a failure judgement is made.