OBD-II code · Powertrain (generic, extended)
P248A Reductant Heater A Sense Circuit Low
Reductant Heater A Sense Circuit Low: the signal voltage is below the expected range. The reductant (DEF/AdBlue) heater keeps the urea fluid from freezing; a fault can impair SCR dosing in cold conditions.
Is it safe to drive with P248A?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySense line shorted to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
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 Heater A
Related codes
- P248CReductant Heater B Sense Circuit Low
- P2487Exhaust Gas Temperature Sensor Circuit High Bank 2 Sensor 5
- P2488Exhaust Gas Temperature Sensor Circuit Range or Performance Bank 2 Sensor 5
- P2489Exhaust Gas Temperature Sensor Circuit Intermittent or Erratic Bank 2 Sensor 5
- P248BReductant Heater A Sense Circuit High
- P248DReductant Heater B Sense Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.