Ford DTC P1138 – Lack of Downstream Heated Oxygen Sensor Switch – Sensor Indicates Rich – Bank No. 1
DTC P1138 meaning on Ford
- DTC: P1138
- Definition: Lack of Downstream Heated Oxygen Sensor Switch – Sensor Indicates Rich – Bank No. 1
- Meaning: The downstream oxygen sensor in Bank 1 is indicating a rich air-fuel mixture condition, which means there is an excess of fuel in the exhaust gases.
Ford DTC P1138 symptoms
- Check Engine Light (MIL) illuminated
- Decreased fuel efficiency
- Rough idling or engine misfires
- Increased emissions
Ford DTC P1138 causes
- Faulty downstream heated oxygen sensor
- Rich air-fuel mixture due to issues with fuel injectors
- Vacuum leaks in the intake system
- Issues with the engine’s air intake system
Ford DTC P1138 seriousness
- Seriousness: While the vehicle may still be operable with this issue, it can lead to decreased fuel efficiency and increased emissions, potentially causing long-term damage to the engine and catalytic converter.
How to diagnose DTC P1138 on Ford
- Use an OBD-II scanner to retrieve the DTC P1138 code
- Inspect the downstream heated oxygen sensor in Bank 1 for any signs of damage or contamination
- Check for vacuum leaks in the intake system
- Inspect the fuel injectors for proper operation
How to fix DTC P1138 on Ford
- Replace the downstream heated oxygen sensor in Bank 1 if faulty
- Clean or replace fuel injectors if necessary
- Repair any vacuum leaks in the intake system
- Ensure the engine’s air intake system is functioning correctly
How to erase DTC P1138 on Ford
- After fixing the underlying issue causing DTC P1138, use an OBD-II scanner to clear the code
- Drive the vehicle to allow the system to retest and ensure the code does not return
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