P0402: Exhaust Gas Recirculation Flow Excessive Detected
Can you still drive? Yes, but the engine may run poorly and stall at idle. Avoid driving in situations where stalling could be dangerous.
What Does P0402 Mean?
Code P0402 means the ECM has detected that the EGR (Exhaust Gas Recirculation) system is allowing too much exhaust gas to recirculate back into the intake manifold. Excessive EGR flow dilutes the air-fuel mixture too much, causing rough running and poor performance. This is the opposite of insufficient EGR flow.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- EGR valve stuck open
- Faulty EGR vacuum solenoid
- Clogged EGR passages causing incorrect pressure readings
- Defective EGR position sensor
- Vacuum line leak to EGR valve
Symptoms
- Check engine light on
- Rough idle
- Engine hesitation or surging
- Poor acceleration
- Engine stalling at idle
Diagnostic Steps
- 1Check for additional EGR-related codes
- 2Inspect the EGR valve for carbon buildup or mechanical failure
- 3Verify the EGR valve closes completely when commanded off
- 4Test the EGR vacuum solenoid operation
- 5Check vacuum lines to the EGR valve for leaks or misrouting
- 6Monitor EGR position sensor readings with a scan tool
Recommended Parts & Tools
EGR vacuum solenoid
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $100 - $500 |
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Chat with AI About P0402Commonly Affected Vehicles
Related Recalls
1 Active Recall — 2026 Ford F-150
The following NHTSA safety recalls have been issued for this vehicle. Contact your dealer to check if your vehicle is affected.
ELECTRICAL SYSTEM: INTEGRATED TRAILER BRAKE CONTROL
Ford Motor Company (Ford) is recalling certain 2021-2026 F-150, 2022-2026 F-250 SD, F-350 SD, F-450 SD, F-550 SD, Maverick, 2024-2026 Ranger, 2023-2026 F-600 SD, 2022-2027 Lincoln Navigator, Expedition, and 2026 E-Transit vehicles. When towing a trailer, the integrated trailer module (ITRM) may lose communication with the vehicle, possibly causing a loss of brake and turn signal lights, or a loss of brake function. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 108, " Lamps, Reflective Devices, and Associated Equipment."
Remedy: The integrated trailer module software will be updated by a dealer, or through an over-the-air (OTA) update, free of charge. Owner notification letters are expected to be mailed March 17, 2026. Owners may contact Ford customer service at 1-866-436-7332. Ford's number for this recall is 26C10. Vehicle Identification Numbers (VINs) involved in this recall will be searchable on NHTSA.gov beginning March 17, 2026.
Data provided by the National Highway Traffic Safety Administration (NHTSA).
Frequently Asked Questions
What does the EGR system do?
The EGR system recirculates a small amount of exhaust gas back into the combustion chambers to lower combustion temperatures and reduce nitrogen oxide (NOx) emissions.
Can I clean the EGR valve instead of replacing it?
Yes, in many cases a thorough cleaning of the EGR valve and passages can resolve the issue. Carbon buildup is a common cause of EGR problems, and cleaning can restore proper operation.
Community Fix Reports
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