Diagnostic Trouble Code (DTC) Information

ECM-2A2A REAR HEATED OXYGEN SENSOR (HO2S) PREHEATING
DIAGNOSTIC TROUBLE CODE (DTC) INFORMATION




Condition
The control module controls preheating by pulsing the current to the PTC-element. Pulse lengths are dependent on Heated Oxygen Sensor (HO2S) temperature.
Diagnostic Trouble Code (DTC) ECM-2A2A is stored if the control module registers that the signal is constantly 2.5 V, higher than 3.5 V at current pulse or lower than 2.3 V at no pulse.
The control module also registers the Heated Oxygen Sensor (HO2S) temperature by measuring resistance in the PTC-element. The probe temperature is then compared with a calculated temperature.
Diagnostic Trouble Code (DTC) ECM-2A2A is stored for a faulty signal if the control module registers that the actual probe temperature is lower than the calculated temperature.

Condition
- fuel trim shut off.

Possible source

Signal too high:
- short-circuit to supply voltage in the signal cable
- defective Heated Oxygen Sensor (HO2S).

Signal too low:
- short-circuit to ground in the signal cable
- defective Heated Oxygen Sensor (HO2S).

Signal missing:
- contact resistance and oxidation
- open-circuit in power supply from system relay.

Faulty signal:
- defective Heated Oxygen Sensor (HO2S).

Condition
- MIL-lamp lights.