OBD-II code · Powertrain (generic, extended)
P246F Reductant System Cold Start Performance
At cold start the SCR system is unable to begin reductant dosing within the required time. Typical cause on diesel cars in winter — frozen AdBlue in the tank or lines, failed tank heater, or a slow-warming SCR catalyst.
Is it safe to drive with P246F?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyAdBlue frozen — tank or line heater not working
- PossibleSCR catalyst slow to reach light-off
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
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Adblue Tank Heater, Adblue Lines, Scr Catalyst
Related codes
- P246CParticulate Filter Restriction Forced Limited Power Bank 1
- P246DParticulate Filter Pressure Sensor A and B Correlation
- P246EExhaust Gas Temperature Sensor Circuit Bank 1 Sensor 4
- P2470Exhaust Gas Temperature Sensor Circuit Intermittent Bank 1 Sensor 3
- P2471Exhaust Gas Temperature Sensor Circuit Range/Performance Bank 1 Sensor 3
- P2472Exhaust Gas Temperature Sensor Circuit Low Bank 1 Sensor 3
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.