P2239 — O2 sensor positive-current control circuit, bank 1 sensor 1 — high electrical level

P2239 concerns O2 sensor positive-current control circuit, bank 1 sensor 1. The monitor reports an electrical level above its expected range. Positive-current control names a sensing circuit function. The high electrical finding does not directly prove a rich or lean air–fuel mixture.

Affected system: Oxygen-sensor monitoring

Symptoms

• Warning light may illuminate
• Related system function may be impaired
• Vehicle-specific symptoms vary

Possible causes

• Implausible sensor or switch signal, poor ground, connector corrosion, or wiring damage
• Related wiring, connector, power or ground fault
• Vehicle-specific mechanical or control issue

What to check

• Record stored and pending codes and freeze-frame data
• Compare the named sensor or switch signal with actual operating conditions; inspect the connector, reference supply, ground and harness.
• Confirm measured values against the vehicle service information
• Retest under the conditions that set the code
• Compare the named sensor or switch signal with actual operating conditions; inspect the connector, reference supply, ground and harness.
• Repair the verified cause and confirm the code does not return

Also written as: P2239-00, P223900 (some scan tools add the fault-type byte, e.g. -00).