P2048
Reductant Injection Valve Circuit Low Bank 1 Unit 1
Diesel exhaust / SCR emissions
Generic OBD-II
Medium
What it means
P2048 means the PCM detected low voltage (a short-to-ground or open) on the reductant injection valve circuit for bank 1, unit 1 — the DEF injector on a diesel SCR system. This injector meters diesel exhaust fluid into the exhaust to reduce NOx. The fault mainly affects emissions, but diesels often respond with warnings and a power derate. The engine still starts and runs.
Medium
Can I keep driving? Drivable at first, but diesel SCR faults often trigger a power derate and eventual no-restart; repair promptly.
Common symptoms
What you'll notice
- Check-engine light on
- SCR / emissions or DEF warning message
- Reduced engine power (derate) if the fault persists
- Higher tailpipe NOx / failed emissions test
Common causes
Most likely first
- Reductant injection valve (DEF injector) circuit shorted to ground or openLikely
- Damaged wiring or corroded connector at the injectorCommon
- Failed reductant injection valveCommon
- Poor ground or power feed to the injector circuitLess often
- Faulty DEF control module / PCM (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and inspect the injector wiring and connector for a short-to-ground or open.
- Measure the injector's resistance and the circuit voltage against spec.
- Repair any damaged wiring, poor ground, or corroded connector.
- Replace the reductant injection valve if it tests out of range.
- Clear the code and re-test; consider the control module only after the circuit checks out.
FAQ
Quick answers
Is it safe to drive with P2048?+
Briefly, yes, but SCR/DEF faults usually force a power derate and can prevent restart after enough drive cycles, so fix it soon.
Can I just clear P2048?+
It returns until the injector or its circuit is repaired; clearing won't stop the derate.
Related codes
Often seen with P2048
Read & clear P2048 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