P0403 — Exhaust Gas Recirculation Flow Excessive Detected
Can drive — fix at your convenience.
What P0403 means
This code means the engine is detecting more exhaust gas recirculation (EGR) flow than it should, often because an EGR valve is stuck open or the system is leaking exhaust into the intake. Common fixes include cleaning or replacing the EGR valve, clearing carbon from the passages, or repairing a stuck position sensor. It's an emissions-related code and is usually a straightforward repair.
Common symptoms
- Check engine light is on
- Rough or unstable idle
- Engine stalls at stops or low speed
- Slight loss of power or hesitation
- Reduced fuel economy
Common causes
- EGR valve stuck open
- Carbon buildup holding the EGR valve open
- Faulty EGR position sensor
- Leaking EGR valve gasket or pipe
- Wiring or vacuum control fault on the EGR system
Typical repair cost
$150 – $500
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0403 code?
Yes, you can usually drive normally for a while since this is an emissions issue. You may notice a rough idle or occasional stalling at stops. Have it repaired within a week or two to protect fuel economy and pass emissions testing.
How much does it cost to fix a P0403 code?
Repairs typically run $150 to $500. Cleaning the EGR valve and passages is the cheaper option, while a full EGR valve replacement with labor reaches the higher end.
Is a P0403 code serious?
It's a low-severity, emissions-related code, so it's not an immediate danger. However, the rough idle and stalling can be annoying and it will fail a smog check, so it's worth fixing soon.
What causes excessive EGR flow in P0403?
Most often the EGR valve is stuck open, frequently from carbon buildup, letting too much exhaust into the intake. A leaking gasket or a faulty position sensor reporting the wrong flow can also trigger it.