OBD-II code · Powertrain (generic, extended)
P2C7A SCR NOx Catalyst Efficiency Below Threshold Bank 1 Catalyst 2
The ECM detects that the conversion efficiency of the second SCR catalyst on bank 1 is below the calibrated threshold. NOx slip past catalyst 2 is too high.
Is it safe to drive with P2C7A?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyCatalyst 2 aged or contaminated
- PossibleReductant dosing insufficient for cat 2
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 2–10 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Scr Catalyst B1 Cat2, Reductant Dosing Unit
Related codes
- P2C77Active Grille Air Shutter D Control Circuit Range/Performance
- P2C78Active Grille Air Shutter Module D Over Temperature
- P2C79NOx Adsorber - Sulfur Limit Exceeded
- P2C7BTurbocharger Turbine Inlet Valve Control Performance
- P2C7CTurbocharger Turbine Inlet Valve Supply Circuit Low
- P2C7DTurbocharger Turbine Inlet Valve Motor Driver High Current
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.