Possible Causes
WARNING: This page is about a different car, the 2003 Toyota 4Runner. However, it is still accessible from the selected car via links, so may be relevant.
DTCs P0037 and P0057 will set when heater current is 0.25 amp or less when heater operates with +B voltage of 11.5 volts or more (one trip detection logic).
DTCs P0038 and P0058 will set when heater current exceeds 2 amps when heater operates (one trip logic detection).
Possible causes are:
- Open or short in heater circuit of heated oxygen sensor.
- Defective heated oxygen sensor heater.
- Defective EFI relay.
- Defective ECM.