P206C code meaning
Reductant Quality Sensor Circuit Low
Powertrain system Generic code P20xx codes Check engine light
What P206C means
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.
P206C at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P206C
- 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
Common causes of P206C
- Most 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
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Reductant quality sensor
What each part of P206C means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| 6C | The exact fault in that area. |
What to do next
- Note P206C and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P206C
What does P206C mean?
P206C means "Reductant Quality Sensor Circuit Low". P206C is the low-side fault of the quality sensor, read in two ways. It is a generic code, so it means the same on every make.
Is it safe to drive with P206C?
Drive gently and only to a workshop. With P206C the car can go into limp mode (reduced power) to protect itself.
Will P206C fail an emissions test?
Yes, it can. P206C is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P206C to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P206C clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.