Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Circuit Description
PCM will test EGR system during deceleration by momentarily commanding EGR valve to open. The pressure in intake manifold increases when EGR valve is open. PCM monitors MAP sensor signal during EGR system diagnostic in order to determine amount of EGR flow. PCM calculates an error based on the difference between actual MAP increase and a predetermined value, and records the error and adjusts an internal fail counter towards the fail threshold if error is too great.
PCM sets DTC when the fail counter exceeds the fail threshold. The number of test samples required to exceed the fail threshold varies according to magnitude of detected flow errors.
PCM allows only one EGR flow test sample to be taken during an ignition cycle. PCM will allow 12 test samples during the first ignition cycle in order to aid in verifying a repair after battery is disconnected or after performing CLEAR INFO on scan tool.
DTC will set when change in MAP is less than a predetermined value during EGR flow test.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.