P040F
EGR Temperature Sensor A/B Correlation
EGR temperature sensors A and B disagree by more than the allowed tolerance over a drive cycle. EGR mixes inert exhaust into intake to lower combustion peak temperature — too little raises NOx, too much causes misfires and rough running.
EGR temperature sensors A and B disagree by more than the allowed tolerance over a drive cycle. EGR mixes inert exhaust into intake to lower combustion peak temperature — too little raises NOx, too much causes misfires and rough running.
Common causes
- high
One sensor drifts
One of the most commonly reported causes for this code — check this first.
Typical part cost: $70-550
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First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
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Related codes
See related trouble codes
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Frequently asked questions
What does P040F mean?
P040F means "EGR Temperature Sensor A/B Correlation". It is a generic OBD-II code that points to a fault in the auxiliary emission controls.
What are the most common causes of P040F?
one sensor drifts — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.
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