P2056
Reductant Injection Valve Circuit/Open Bank 2 Unit 2
SCR / reductant injection (diesel emissions)
Generic OBD-II
Medium
What it means
P2056 means the control module detects an open circuit at the second reductant (diesel exhaust fluid) injector on bank 2. This injector sprays DEF into the exhaust so the SCR catalyst can reduce NOx. The engine still runs, but emissions climb and many diesels will derate power if it stays unresolved. Check the injector wiring and connector for an open before replacing the injector.
Medium
Can I keep driving? Driveable short-term — NOx emissions rise and the diesel may enter reduced power if the SCR fault is not resolved, so repair it soon.
Common symptoms
What you'll notice
- Check-engine light on
- SCR / exhaust-fluid (DEF) warning message or light
- Possible reduced-power (derate) mode if unresolved
- Higher NOx emissions / emissions-test failure
Common causes
Most likely first
- Open circuit in the reductant injector (DEF injector) winding or wiringLikely
- Damaged or corroded connector at the injectorCommon
- Faulty reductant injection valveCommon
- Faulty powertrain control module (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm the fault is on bank 2, unit 2.
- Inspect the injector connector and wiring for an open circuit, damage, or corrosion.
- Measure the reductant injector resistance and compare to spec; an open reading confirms a bad injector.
- Replace the reductant injection valve if it is open or out of range; consider the PCM only if wiring and injector are good.
FAQ
Quick answers
Is it safe to drive with P2056?+
For short trips, yes, but the SCR system cannot dose DEF properly, so emissions rise and the vehicle may derate. Get it repaired soon.
Can I just clear P2056?+
It will return until the open circuit or injector is repaired, because the injector still cannot be driven.
Related codes
Often seen with P2056
Read & clear P2056 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