OBD-II code · Powertrain (generic, extended)
P206D Reductant Quality Sensor Circuit High
DEF quality sensor reads above upper plausibility — open signal or short to B+. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P206D?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyOpen signal line
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–3 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Quality Sensor
Related codes
- P206AReductant Quality Sensor Circuit
- P206BReductant Quality Sensor Circuit Range/Performance
- P206CReductant Quality Sensor Circuit Low
- P206EIntake Manifold Tuning (IMT) Valve Stuck Open (Bank 2)
- P206FIntake Manifold Tuning (IMT) Valve Stuck Closed (Bank 2)
- P2070Intake Manifold Tuning (IMT) Valve Stuck Open (Bank 1)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.