OBD
P2D1C
Cold Start EGR A/B Ratio Performance
What it means
P2D1C means Cold Start EGR A/B Ratio Performance.
Check these first
- Carbon clogging the EGR passages
- A stuck EGR valve
- A failed EGR position sensor
- A leaking EGR gasket
- A faulty EGR temperature sensor
What to do next
- Command the EGR valve with a scan tool and watch it move
- Check the EGR passages for carbon
- Inspect the EGR gasket for leaks
- Test the EGR position sensor
- Replace the EGR valve if it does not move
- Clear the code and retest
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Updated
Generic SAE J2012 definition. Last updated 2026-10-10.