P04D9

Symptoms

• Check Engine Light Is On
• Loss of engine power
• Unstable operation at idle
• Increased exhaust smoke (especially on diesel engines)
• Possible additional EGR error codes

Causes

• EGR valve clogged with carbon deposits
• Clogged exhaust gas recirculation path
• Faulty EGR valve (does not open)
• Leak in the exhaust system in front of the EGR valve
• Malfunction of the EGR flow or pressure sensor
• EGR cooler clogged

How to Fix

1. Read error codes and check freeze frame data
2. Check the EGR valve for deposits and movement of the rod
3. Clean the EGR valve from carbon deposits (or replace if severely worn)
4. Check and, if necessary, clean the recirculation path
5. Check the integrity of the exhaust system for leaks
6. Check the operation of the EGR valve actuator (pneumatic or electric)
7. Check EGR pressure/flow sensors
8. Reset the error and take a test drive

Related codes

Error P04D9 by Vehicle Brand