P2044

Reductant Temperature Sensor A Circuit Low

Q: Is it safe to drive with P2044?

Mechanically yes — the engine runs fine. But the SCR system may not work correctly, and many diesels begin a derate countdown, so address it before that limits the vehicle.

Q: Can I just clear P2044?

It returns until the sensor or wiring is repaired, and clearing won't stop an emissions derate from recurring.

Emissions (SCR / DEF after-treatment) Generic OBD-II Medium

What it means

P2044 means the reductant (diesel-exhaust-fluid) temperature sensor A is reporting an abnormally low circuit voltage, so the SCR system can't accurately gauge DEF temperature. The engine starts and runs normally, but NOx dosing may be affected and many diesels start a derate countdown if it isn't fixed. The usual cause is a shorted sensor, wiring, or connector.

Medium

Can I keep driving? The engine runs and starts normally, but the SCR system may not dose correctly and some diesels count down to a speed limit — don't leave it unfixed.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
SCR / diesel-exhaust-fluid (DEF) warning message
Higher NOx emissions; may fail an emissions test
Speed / power derate if the fault persists (varies by vehicle)

Common causes

Most likely first

Reductant (DEF) temperature sensor A shorted or reading lowLikely
Sensor circuit wiring shorted to groundCommon
Corroded or loose connector at the DEF tank / sensorCommon
Failed reductant temperature sensorLess often
PCM / dosing control module fault (least likely)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and check for companion reductant codes (P2042, P2043).
Inspect the DEF temperature sensor connector and wiring for a short to ground or corrosion.
Compare the sensor's reported temperature to ambient/other sensors with a scan tool.
Replace the reductant temperature sensor if out of spec, then clear and re-test.

FAQ

Quick answers

Is it safe to drive with P2044?+

Mechanically yes — the engine runs fine. But the SCR system may not work correctly, and many diesels begin a derate countdown, so address it before that limits the vehicle.

Can I just clear P2044?+

It returns until the sensor or wiring is repaired, and clearing won't stop an emissions derate from recurring.

Read & clear P2044 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX