P2D45Reductant Temperature Too Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2D45 means the diesel exhaust fluid in the tank does not warm up as it should while the tank heater is working, so frozen or very cold fluid cannot be dosed. GM uses the code in its diesel OBD tables from 2021 to 2025 in two variants. In the separate reductant control module, after over 28,800 s engine-off, with fluid between -40 and -14 °C, more than 5 L in the tank and a heater command of at least 10 W, the module compares the measured mean temperature with what a just-acceptable heater would reach; staying below it fails the test, judged once per trip on a 600 s basis. A 2023 engine module variant checks that the tank warms from a start below 0 °C. Both are Type B. Heater circuit faults: P20B9 ff.; too hot: P24FF.
- What you may notice
- MIL after two trips in cold weather
- DEF or SCR warning message, dosing delayed
- Possible countdown to speed limitation if the fault persists
- Likely causes
- LikelyTank heater element degraded or partly failed
- PossibleLow supply voltage to the heater, e.g. weak battery or poor ground
- RareTank temperature sensor reading too low
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.