P05EBCold Start SCR NOx Catalyst Inlet Temperature Too Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- After a cold start a diesel heats its exhaust actively – retarded and post injection, intake or exhaust throttling, higher idle, EGR cooler bypass – so the SCR catalyst quickly reaches the temperature at which urea dosing can start (around 180–200 °C). P05EB sets when the measured temperature at the SCR inlet stays below the expected or modelled value within a set time after the start: the heating strategy is not working. CARB requires this 'catalyst warm-up' monitor for light-duty diesels from model year 2026 (20 %) to 2028 (100 %); GM 2025 and Ford 2023 tables do not contain the code yet. Volvo Trucks used it on 2016–17 heavy-duty engines and advised a software check instead of replacing parts. The lamp comes on; no power limitation from this code alone is known.
- What you may notice
- Check engine light on
- Usually no driving symptoms
- Higher NOx emissions after cold start (not noticeable)
- Likely causes
- LikelyEngine module software or calibration (false trigger)
- PossibleExhaust temperature sensor before the SCR reads low or slow
- PossibleHeating measure not effective: throttle, EGR cooler bypass or turbo vanes sticking
- RarePost or retarded injection not effective (injectors)
- RareExhaust leak before the sensor or extremely cold conditions
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.