OBD-II code · Powertrain (generic, extended)
P2C79 NOx Adsorber - Sulfur Limit Exceeded
The ECM detects that the cumulative sulfur load on the NOx adsorber catalyst exceeds the calibrated threshold. Desulfation regeneration is required to restore catalyst function.
Is it safe to drive with P2C79?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyOperation with high-sulfur fuel
- PossibleDesulfation regen strategy disabled or failed
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–6 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Nox Adsorber Catalyst
Related codes
- P2C76Active Grille Air Shutter D Stuck On
- P2C77Active Grille Air Shutter D Control Circuit Range/Performance
- P2C78Active Grille Air Shutter Module D Over Temperature
- P2C7ASCR NOx Catalyst Efficiency Below Threshold Bank 1 Catalyst 2
- P2C7BTurbocharger Turbine Inlet Valve Control Performance
- P2C7CTurbocharger Turbine Inlet Valve Supply Circuit Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.