P0402 — Exhaust Gas Recirculation Flow Excessive

P0402 means too much exhaust gas is flowing back into the intake. A stuck-open EGR valve or a carbon-jammed passage is nearly always responsible.

Cost range: $100–$700. Severity: medium. Safe to drive? Yes but expect rough idle and stalling, especially at low speeds.

Most common causes of P0402

1. EGR valve stuck open — Carbon deposits keep the pintle off its seat. ($200–$600)
2. Failed EGR pressure/position sensor — Misreports flow to the ECM. ($100–$300)
3. Faulty EGR vacuum control solenoid — Applies vacuum when it shouldn't. ($80–$250)
4. Cracked EGR diaphragm — Valve can't close fully. ($200–$600)

Symptoms drivers report with P0402

• Rough idle
• Stalling at stops
• Hesitation
• Poor fuel economy