P0167: O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 3)
Check Engine Light illuminated; potential reduced fuel efficiency and emissions performance; generally does not prevent vehicle operation.
Overview
P0167 indicates a malfunction in the oxygen sensor heater circuit on Bank 2 Sensor 3, often due to heater element failure, wiring issues, blown fuse, or connector damage.
Common Symptoms
- Check Engine Light (MIL) illuminated
- Reduced fuel efficiency
- Rough idle or hesitation (especially on cold start)
- Possible failed emissions inspection
Most Common Causes
Internal heater failure in the Bank 2 Sensor 3 oxygen sensor can cause open or out-of-spec resistance.
Damaged, corroded, or chafed wires/connectors in the heater circuit interrupt power/ground.
A blown fuse can interrupt power to the heater; must verify root cause to prevent repeat failures.
Poor electrical contact at the sensor harness can mimic heater circuit failure.
Rare control module failure or software error affecting heater drive circuit.
Diagnostic Steps
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Confirm presence of P0167 using an OBD-II scanner and note any additional related codes.Expected: P0167 active; other related codes may appear (e.g., P0166, P0168).Interpretation: Verifies code and checks for simultaneous faults.
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Perform a visual inspection of the Bank 2 Sensor 3 oxygen sensor harness and connector.Expected: Look for damaged, frayed wires, corrosion, or loose pins.Interpretation: Physical damage supports wiring/connector cause.
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Check for proper power supply (approx. 12 V) to the heater circuit with ignition on.Expected: Battery voltage present at heater power terminal.Interpretation: No voltage indicates power supply or fuse issue.
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Measure resistance of the oxygen sensor heater element with a multimeter.Expected: Resistance within manufacturer specification (~5-14 ohms typical).Interpretation: Out-of-spec or infinite resistance indicates faulty heater or open circuit.
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Check and replace any blown fuses related to the heater circuit.Expected: Fuse intact; if blown, replace after diagnosing root cause.Interpretation: Fuse issues point to short or internal sensor fault.
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If all above tests pass, evaluate PCM/ECM output using advanced scan tool.Expected: Proper commanded heater operation.Interpretation: Abnormal results may indicate control module issue.
Repair Solutions
OEM quality sensor recommended to ensure correct heater resistance specifications.
Cost varies based on extent of wiring harness repair needed.
Verify circuit first to avoid repeated fuse failures.
Only when confirmed by advanced diagnostics; rare.
Common Misdiagnoses
Avoid these common diagnostic mistakes:
- Assuming upstream O2 sensor failure instead of downstream heater circuit issue
- Replacing sensor without checking wiring and fuses first
- Blaming unrelated engine performance codes without correlating live data
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