What the P2631 code means?
P2631 is an OBD-II generic code for the engine control module (ECM) detecting an open or short circuit in the Air Fuel Radio (A/F) or O2 sensor, causing a high voltage at the signal wire to the ECM.
What causes the P2631 code?
The ECM monitors the A/F or O2 sensor signal wire voltage and will set the code of higher voltage than expected is seen.
The O2 sensor signal return wire shorted to the 5 volt reference wire.
What are the symptoms of the P2631 code?
The Check Engine light will be illuminated and the code is set in ECM memory as a fault.
The engine may not be able to go into closed fuel loop and will go into failure mode fuel control.
The engine may run good but may have very minor drivability symptoms like hesitation or lowered fuel mileage.
How does a mechanic diagnose the P2631 code?
Scans for codes and documents the code in the ECM and looks at the freeze frame data for failure.
Checks the O2 sensor and wiring harness for cuts into the harness causing the short.
Tests the wiring and sensor for shorted or corroded connectors and wiring.
Scans the O2 sensors and checks the voltage return on the signal wire for short to reference voltage.
Common mistakes when diagnosing the P2631 code?
Clearing ECM memory codes before checking the freeze frame data for the main failure problem, so the failure may be duplicated and repaired
Replacing the A/F or O2 sensor without checking the wiring connector for short to reference voltage
How serious is the P2631 code?
Code P2631 is a code indicating the A/F O2 sensor return signal is shorted to power and cannot generate the correct signal to the ECM for fuel control. The engine will not run in closed loop as long as the problem is happening.
What repairs can fix the P2631 code?
- Replace the A/F O2 sensor.
- Repair a shorted wire harness to the A/F O2 sensor.
Additional comments for consideration regarding the P2631 code
Code P2631 is caused most commonly from an internal short to reference voltage in the A/F or O2 sensor. The sensor can be called an A/F sensor or an O2 sensor depending on manufacturer.
Need help with a P2631 code?
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