OBD-II Generic Error Code P0402: How to Fix It

Q: What does error code P0402 mean?

P0402 indicates excessive EGR flow. The ECM detects that more exhaust gas is recirculating than commanded, often due to a stuck-open EGR valve or blocked passages.

Q: Can I drive with a P0402 code?

Yes, but you may notice rough idle, hesitation, or poor fuel economy. It's best to fix it promptly to avoid further issues and failed emissions tests.

Q: How much does it cost to fix P0402?

If you DIY, the cost is minimal (cleaner, gaskets). If you replace the EGR valve, parts range from $50-$200. Professional labor adds $100-$200.

Q: Will cleaning the EGR valve fix P0402?

Often yes, if carbon buildup is the cause. If cleaning doesn't work, the valve or sensor may need replacement.

Q: What tools do I need to diagnose P0402?

An OBD2 scanner to read codes, a hand vacuum pump to test vacuum-operated valves, and a multimeter for electronic sensors.

Abstract

Error code P0402 means the engine control module (ECM) has detected too much exhaust gas recirculation (EGR) flow. This can cause rough idle, hesitation, and increased emissions. Common causes are a stuck-open EGR valve, blocked EGR passages, or a faulty EGR position sensor.