Meaning

Exhaust gas recirculation (EGR) flow is below the expected value: the valve or passages are clogged with carbon.

Common causes

• Carbon-fouled or stuck EGR valve
• Soot-clogged EGR passages
• Faulty EGR position/pressure (DPFE) sensor
• Vacuum or control-signal problem
• Clogged EGR cooler

Symptoms

• Check-engine light
• Knock or pinging
• Rough idle
• High NOx at the emissions test
• Sometimes minimal symptoms

Severity

What to do

1. Clean the EGR valve and passages of carbon
2. Check the EGR/DPFE sensor
3. Verify the vacuum or electrical control signal

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