Applicable Systems
OBD-II
Symptoms
EGR system not flowing enough exhaust gas; NOx emissions increase; engine may ping under load.
Possible Causes
- EGR valve stuck closed
- EGR passage clogged with carbon
- EGR vacuum line disconnected (vacuum operated EGR)
Troubleshooting Steps
- Step 1: Check EGR valve operation with vacuum/ electrical test
Valve opens when activated - Step 2: Inspect EGR passages for carbon blockage
Passages clear - Step 3: Check EGR vacuum lines (if vacuum operated)
Lines connected and intact - Step 4: Clean EGR valve and passages
Valve and passages clean - Step 5: Replace EGR valve if stuck
EGR flow within spec
How to Reset
Clear with OBD-II scanner after repair; may need drive cycle for EGR monitor.
Common Replacement Parts
- EGR Valve (OEM spec)
- EGR Gasket
Frequently Asked Questions
- Q: What does EGR do?
Recirculates small amount of exhaust gas back into intake to lower combustion temperature, reducing NOx emissions. Active during cruise and light acceleration.
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Source: SAE J2012 standard DTC list + OBD-II portal
Category: OBD-II
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