P2043
Reductant Temperature Sensor A Circuit Range/Performance
Emissions control (SCR/DEF)
Generic OBD-II
Medium
What it means
P2043 means the reductant (diesel exhaust fluid / AdBlue) temperature sensor A is reporting a value that's out of the expected range. This sensor tracks DEF temperature so the SCR system can dose correctly and avoid dosing frozen fluid. The engine still runs, but because it's an emissions fault many diesels will derate or restrict restarts if it isn't repaired.
Medium
Can I keep driving? Yes for now, but this is a diesel emissions (SCR/DEF) fault — many diesels will eventually derate power or block a restart if it isn't fixed. Repair promptly.
Common symptoms
What you'll notice
- Check-engine light on
- Often no immediate change in drivability
- Possible SCR/DEF warning messages
- Reduced power (derate) or restart limits if left unrepaired
Common causes
Most likely first
- Faulty reductant (DEF/AdBlue) temperature sensor A giving an out-of-range valueLikely
- Damaged or corroded wiring/connectors at the reductant temperature sensorCommon
- Poor electrical connection in the sensor circuitCommon
- Frozen or contaminated reductant fluid skewing readingsLess often
- Faulty powertrain control module (PCM)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and compare the reductant temperature sensor A reading to ambient/expected values.
- Inspect the sensor connector and harness for corrosion, damage, or looseness; repair as needed.
- Check DEF fluid level and quality; top up or correct contamination.
- Replace the reductant temperature sensor A if it reads out of range with good wiring.
- Clear the code and re-run the drive cycle to confirm.
FAQ
Quick answers
Is it safe to drive with P2043?+
It's drivable in the short term, but diesel emissions faults can trigger power derate or a no-restart countdown, so get it repaired soon.
Can I just clear P2043?+
Clearing it won't help if the sensor or wiring is faulty — it returns after the monitor re-runs. Fix the underlying circuit.
Related codes
Often seen with P2043
Read & clear P2043 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX