Code
P0404
Emissions / EGR
EGR valve range / performance
The EGR valve is not reaching the commanded position.
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Most likely causes
- Carbon in the EGR valve
- Faulty position sensor
- Sticky valve
Symptoms you may notice
- Check engine light
- Rough idle
Checks to run
- Clean the EGR
- Test position sensor
- Verify movement
Tools you may need
EGR cleaner
Always diagnose before replacing. Codes share symptoms; confirm the cause with measurements before buying parts.