Diagnostic trouble code (DTC) information
Condition
The control module controls rear heated oxygen sensor (HO2S) preheating by pulsing the current to the positive temperature coefficient (PTC) element in the heated oxygen sensor (HO2S). Pulse lengths are dependent on the temperature of the heated oxygen sensor (H02S).
Diagnostic trouble code (DTC) ECM-2A20 (bank 1) is stored if the control module registers that the signal is higher than a particular value when preheating is activate (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
- 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 the power supply from the system relay
- Defective heated oxygen sensor (HO2S).
Fault symptom[s]
- The malfunction indicator lamp (MIL) lights.