P205BReductant Tank Temperature Sensor A Circuit Range/Performance
- 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
- P205B is the rationality check of the DEF tank temperature: after a long cold soak every sensor should read about the same, so a tank value far off the rest is flagged. GM's 6.6L LML compares it with fuel temperature after 28,800 s engine off (beyond +35/−35 °C, Type B); GM's 2018 diesel table uses the exhaust gas temperature average (>35 °C, Type A), and the 2025 DEF controller needs at least four reference sensors and over 8 h off (>30 °C, Type A). Ford's 2023 diesels compare it with the quality sensor at start (>40 °C), VW's Touareg with outside air. Volvo/Mack (KC-2107) have it re-run before replacing the level sensor, and Ford (2019 6.7L), Land Rover (2016 TDV6) and GM (2021–22 3.0L) cured cases by software. Circuit faults are P205C/P205D.
- What you may notice
- MIL, sometimes with an emissions service message
- Usually no change in driving
- Likely causes
- LikelyCalibration error, fixed by reprogramming
- PossibleTank temperature sensor reading off (offset or gain)
- PossibleFrozen tank or low fill level distorting the reading
- RareFaulty reference sensor (fuel, exhaust or quality sensor)
- 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: €0 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.