P206DReductant Quality Sensor Circuit High
- 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
- P206D is the upper limit counterpart of P206C. In GM's 2018 diesel table it is electrical: the piezo input of the ultrasonic quality sensor above 4.5 V in 40 of 50 samples, Type A. Ford's 2023 diesels set it when filtered urea concentration reads 60 % or more for over 900 s, which real DEF never reaches, so either the sensor or a foreign fluid is to blame. GM PIP5635 for 2019 Colorado and Canyon 2.8L names a false cause: urea crystals that form around the sensor when the fluid freezes and thaws. Before repairs, sensor status should read OK, concentration 28 to 40 % and the tank above 5 °C; if not, warm the truck indoors and drive it in traffic for 10 minutes. FCA STAR case S2025000006 for 2020 Wrangler and Gladiator diesels calls the code mainly electrical but asks for a refractometer and hydrocarbon strip test too.
- What you may notice
- MIL and DEF or emission system warning
- Fault often after cold nights
- Countdown toward speed limit or no-restart
- Likely causes
- LikelyUrea crystals around the sensor after freeze and thaw
- PossibleSensor signal open or shorted to voltage, failed sensor
- PossibleForeign or over-concentrated fluid in the tank
- 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 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.