P0404

Exhaust Gas Recirculation Circuit Range/Performance

OBD-II diagnostic trouble code P0404indicates a fault detected by the vehicle's onboard computer. This code applies to all OBD-II compliant vehicles and should be addressed promptly to avoid potential engine or emissions system damage.

Severity Level 3 — Moderate

This code indicates a moderate issue that may affect vehicle performance and fuel economy. Continued driving is possible in most cases, but prompt diagnosis and repair are recommended to prevent further damage.

Common Symptoms

• Check Engine Light on
• Engine surge or hesitation at steady throttle
• Rough idle, may stall
• Engine knock under acceleration
• Failed emissions test

Possible Causes

• Faulty EGR valve position sensor — internal feedback potentiometer worn, reports incorrect position
• Carbon buildup preventing EGR valve from reaching commanded position
• Damaged wiring or poor connection at EGR valve electrical connector
• Faulty EGR control solenoid
• PCM software issue requiring update/reflash

Common Fixes

• Replace EGR valve assembly (includes position sensor) ($150-450)
• Clean EGR valve and passages of carbon deposits ($100-350)
• Repair damaged wiring or connector at EGR valve ($30-150)
• Perform PCM software update ($80-200 at dealer)

Estimated Repair Cost

These are estimated costs based on generic repair data. Actual costs may vary depending on your vehicle, location, and labor rates.

Explore Repair Costs

Related Discussions

See what other car owners are saying about this code and related repairs.