Catalyst Efficiency Monitor

CATALYST EFFICIENCY MONITOR

The powertrain control module (PCM) monitors the oxidation catalytic converter (OC) during the diesel particulate filter regeneration. The PCM determines if the temperature increase across the catalyst is correct. The PCM uses the OC inlet temperature, measured by exhaust gas temperature bank 1, sensor 1 (EGT11) and the OC outlet temperature, measured by EGT bank 1, sensor 2 (EGT12) to calculate the temperature increase.

The catalyst efficiency monitor is enabled and runs continuously during a regeneration after a short time delay, to allow the OC to light-off. The catalyst efficiency monitor runs only when certain base engine conditions are first satisfied. The typical monitoring duration for this monitor is 2 minutes. Inputs from the crankshaft position (CKP), engine coolant temperature (ECT), EGT11 and EGT12 sensors are required to enable the monitor. The monitor entry conditions include:
- diesel particulate filter regeneration is active
- Engine coolant temperature is greater than 70°C (158°F)
- no fuel injector concerns
- engine speed between 600 and 3,000 RPM
- engine torque between 100 and 900 Nm
- OC inlet temperature 200-500°C (392-932°F)

The PCM continuously monitors the temperature increase. The PCM compares the measured increase against a minimum expected value. The minimum expected value is based on the amount of fuel injected for regeneration. The measured increase is filtered for a short period of time. At the end of this time, the measured increase is compared to the expected increase. If the temperature increase is less than 40% of the minimum expected increase, the monitor has failed.