HO2S Heater Control Circuit High (Bank 2 Sensor 2)
The PCM detected that the heater control circuit for the Bank 2 Sensor 2 oxygen sensor is receiving higher voltage than expected. This prevents the oxygen sensor from heating properly, which affects emissions monitoring and fuel trim calculations.
What You Might Notice
- Check Engine Light (MIL) illumination
- Possible rough idle
- Reduced fuel economy
- Failed emissions test
- No immediate drivability issues in most cases
Most Common Causes
- 1
Faulty Bank 2 Sensor 2 HO2S
The heated oxygen sensor itself is defective or has failed internally, causing incorrect heater circuit voltage readings.
- 2
Short to Battery Voltage in Heater Circuit
The heater control wiring is shorted to positive battery voltage (B+), causing the circuit voltage to exceed normal operating limits.
- 3
PCM or Wiring Harness Defect
Damaged wiring, corroded connectors, or a faulty PCM control driver are sending incorrect voltage commands to the heater circuit.
- 4
Open in Heater Ground Circuit
A broken ground wire or poor ground connection can cause the heater control circuit to appear as high voltage to the PCM.
How to Diagnose It
- 1
Check Faulty Bank 2 Sensor 2 HO2S — The heated oxygen sensor itself is defective or has failed internally, causing incorrect heater circuit voltage readings.
- 2
Check Short to Battery Voltage in Heater Circuit — The heater control wiring is shorted to positive battery voltage (B+), causing the circuit voltage to exceed normal operating limits.
- 3
Check PCM or Wiring Harness Defect — Damaged wiring, corroded connectors, or a faulty PCM control driver are sending incorrect voltage commands to the heater circuit.
- 4
Check Open in Heater Ground Circuit — A broken ground wire or poor ground connection can cause the heater control circuit to appear as high voltage to the PCM.
How to Fix It
- 1
Replace Bank 2 Sensor 2 HO2S
Remove and replace the heated oxygen sensor on Bank 2 (passenger side), Sensor 2 (downstream sensor after catalytic converter). Clear the code and test drive to verify resolution.
- 2
Inspect and Repair Heater Circuit Wiring
Inspect the oxygen sensor heater control wiring harness for damage, corrosion, or shorts to battery voltage. Repair or replace damaged sections and reconnect any loose terminals. Retest after repairs.
- 3
Check and Clean Electrical Connections
Locate the PCM connector and oxygen sensor connectors; clean all corrosion and ensure connections are tight. Poor connections can cause voltage anomalies. Reseat connectors firmly and retest.
- 4
Test PCM Control Circuit
If wiring and sensor are good, use a multimeter to test the PCM's heater control output voltage. If voltage is constantly high even with good sensor and wiring, the PCM driver circuit may be faulty and require replacement.
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