P2049
Reductant Injection Valve Circuit High Bank 1 Unit 1
Diesel exhaust aftertreatment (SCR)
Generic OBD-II
Medium
What it means
P2049 means the aftertreatment controller detected higher-than-expected voltage in the reductant (DEF) injection valve circuit for bank 1, unit 1. This valve sprays diesel exhaust fluid into the exhaust to cut NOx. A high-circuit fault is usually an open or high-resistance wiring problem or a failed injector, and can trigger a power derate to keep emissions in check.
Medium
Can I keep driving? Usually driveable at first, but many diesels reduce power (derate) when reductant dosing fails — repair it before the vehicle limits performance.
Common symptoms
What you'll notice
- Check-engine light on
- SCR / DEF or emissions-system warning message
- Possible reduced power (engine derate)
- Increased NOx / failed emissions readiness
Common causes
Most likely first
- Open circuit or high resistance in the reductant injection valve wiringLikely
- Failed reductant (DEF) injection valveCommon
- Corroded or loose connector at the injectorCommon
- Faulty PCM/aftertreatment control module — less commonLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and inspect the reductant injector connector and wiring for an open or high resistance.
- Check the injector's supply and control circuits with a multimeter for continuity.
- Measure the reductant injection valve resistance against spec and replace it if out of range.
- If wiring and injector are good, have the aftertreatment control module evaluated. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P2049?+
Short-term usually, but the SCR system may derate engine power to protect emissions. Repair it before the vehicle limits performance or restart attempts.
Can I just clear P2049?+
It returns until the wiring or injector fault is repaired, and clearing won't prevent an emissions-related derate from recurring.
Related codes
Often seen with P2049
Read & clear P2049 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