P206CReductant Quality Sensor Circuit 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
- P206C is the low-side fault of the quality sensor, read in two ways. GM treats it as electrical: in its 2018 diesel table the piezo input of the ultrasonic sensor below 0.15 V in 40 of 50 samples sets the code, Type A. Ford uses it as a quality verdict: its 2023 diesels flag P206C when the filtered urea concentration stays at 28 % or less for over 900 s, and Ford SSMs 46890 to 50323 for 6.7L, 3.2L and 3.0L diesels say most cases come from diluted DEF, so the fluid is checked with a refractometer and replaced before parts are swapped, since low concentration also triggers a derate. GM PIP5602 for 2019 Colorado and Canyon 2.8L adds a false trigger: at roughly 30 % fill or less, a long right-hand curve can uncover the sensor; no parts are replaced, the tank is simply filled. Above-range readings belong to P206D.
- What you may notice
- MIL and DEF quality or emission system warning
- Reduced power or speed limit on Ford diesels
- Warning that appears after a long curve and then clears
- Likely causes
- LikelyDiluted or wrong fluid in the DEF tank (Ford definition)
- PossibleLow tank level letting the sensor run dry in curves
- PossibleSensor signal shorted to ground or failed sensor element
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €20 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.