P0400
EGR A Flow
P0400 is an OBD-II diagnostic trouble code meaning: EGR A Flow. Common causes: egr valve clogged, egr solenoid malfunction. Estimated repair cost: $56–167.
Symptoms
- Unstable idle
- Reduced engine power
- Increased fuel consumption
- Detonation (knock) during acceleration
Causes
- EGR valve clogged
- EGR solenoid malfunction
- Broken or damaged wiring harness
- Vacuum leak
- EGR valve position sensor malfunction
- Clogged EGR channels
How to Fix
- Check the condition of the EGR valve and clean or replace if necessary
- Check vacuum lines for leaks
- Check wiring harness and connections
- Check the operation of the EGR solenoid
- Clean EGR channels from carbon deposits
- Check EGR valve position sensor
Related codes
Error P0400 by Vehicle Brand
FAQ
What does the P0400 code mean?
P0400 is an OBD-II diagnostic trouble code that indicates: EGR A Flow
What causes a P0400 error code?
The most common causes of P0400 include: EGR valve clogged; EGR solenoid malfunction; Broken or damaged wiring harness; Vacuum leak.
How do I fix a P0400 diagnostic trouble code?
To fix P0400: Check the condition of the EGR valve and clean or replace if necessary. Check vacuum lines for leaks. Check wiring harness and connections. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P0400?
Limited driving only, diagnose soon
How much does it cost to fix P0400?
The estimated repair cost for P0400 is $56–167. Actual cost depends on your vehicle, location, and labor rates.
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