Exhaust Gas Recirculation Circuit Range/Performance
What does P0404 mean?
The P0404 code means the vehicle's onboard diagnostic system has detected: Exhaust Gas Recirculation Circuit Range/Performance. This is a moderate severity code.
Common Symptoms
- Check Engine Light illuminated
- Rough or fluctuating idle
- Hesitation during acceleration
- Engine stalling at stops
- Failed emissions test
Probable Causes (Ranked by Likelihood)
- Carbon buildup restricting EGR valve movement Very High
- Faulty EGR valve position sensor High
- EGR valve pintle sticking intermittently Moderate
- Incorrect EGR valve installed after replacement Low
Step-by-Step Diagnostic Procedure
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Use a scan tool to command the EGR valve through its full range and monitor position sensor feedback
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Compare commanded position to actual position -- a deviation greater than 10% indicates a problem
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Remove the EGR valve and inspect the pintle for carbon buildup restricting movement
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Check EGR position sensor voltage sweep -- should transition smoothly from closed to open
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Clean the EGR valve and passages, then retest with a scan tool
Frequently Asked Questions
Can I drive with code P0404?
You can drive short distances. The EGR valve is not responding as expected, which can cause rough idle or stalling. If the engine runs rough, avoid driving until repaired.
Is P0404 common on GM trucks?
Yes. GM trucks and SUVs with the 4.8L, 5.3L, and 6.0L V8 engines are particularly prone to P0404 due to carbon buildup on the EGR valve pintle over time.
Can cleaning fix P0404?
Often yes. Removing the EGR valve and thoroughly cleaning carbon deposits from the pintle and passages resolves the range/performance issue. Replace the valve only if cleaning does not restore proper operation.