OBD-II code · Powertrain (generic, extended)
P202A Reductant Tank Heater Control Circuit/Open
The DEF tank heater control circuit is open or has lost continuity — the PCM cannot drive the resistive heater that prevents the DEF (urea) tank from freezing in winter.
Is it safe to drive with P202A?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyHeater element winding open
- PossibleOpen wire between PCM and heater
- Less likelyPin pushed back out of connector body
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
- 0.7–2.5 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Tank Heater, Reductant Tank Harness
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.