Diagnostic Trouble Code (DTC) Information

Diagnostic trouble code (DTC) information ECM-2A20

Condition




The engine control module (ECM) controls preheating by pulsing the current to the positive temperature coefficient (PTC) element in the rear heated oxygen sensor (HO2S). Pulse lengths are dependent on the temperature of the heated oxygen sensor (HO2S).
The diagnostic trouble code (DTC) is stored if the engine control module (ECM) registers that the signal is higher than a particular value when preheating is activated (signal too high) or lower than a certain value when preheating is deactivated (signal too low or signal missing).

Substitute value
- The fuel trim is shut off.

Possible source

Signal too high
- Short-circuit to supply voltage in the signal cable
- Damaged rear heated oxygen sensor (HO2S).

Signal too low
- Short-circuit to ground in the signal cable
- Damaged rear heated oxygen sensor (HO2S).

Signal missing
- Contact resistance and oxidation in the terminals
- Open-circuit in the power supply from the system relay
- Damaged rear heated oxygen sensor (HO2S).

Fault symptom[s]
- Malfunction indicator lamp (MIL) lit.