O2 Sensor Circuit High Voltage

Descripción

This code indicates that the oxygen sensor is sending a voltage signal that is too high. This often means the sensor is detecting too much oxygen, which can lead to the engine running lean (too little fuel).

Pasos de reparación

1. 1 Check for other related diagnostic trouble codes (DTCs) that may indicate a lean condition or fuel system issue, and clear codes to see if P0138 returns.
2. 2 Inspect the wiring and connector to the downstream (Bank 1, Sensor 2) oxygen sensor for damage, corrosion, fraying, or loose connections.
3. 3 Check for exhaust leaks near the oxygen sensor that could affect its readings.
4. 4 Test the oxygen sensor voltage output using a multimeter or scan tool — it should fluctuate between 0.1V and 0.9V; a consistently high voltage (above 0.9V) confirms a faulty sensor.
5. 5 Inspect the fuel system for conditions causing a rich running engine, including a leaking fuel injector, high fuel pressure, or a saturated charcoal canister/purge valve issue.
6. 6 Replace the faulty oxygen sensor (Bank 1, Sensor 2) if voltage is stuck high or readings are erratic.
7. 7 Repair or replace any damaged wiring or connectors in the O2 sensor circuit.
8. 8 If all other components test normal, have the engine control module (ECM) inspected and tested by a professional for internal faults.

Diagnóstico y costo