What it means
Reductant Injection Valve Circuit Low (Bank 2 Unit 2): the signal voltage is below the expected range. This valve doses reductant (DEF/AdBlue) into the exhaust for SCR NOx reduction.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The reductant injection valve for Bank 2, Unit 2 meters DEF/AdBlue into the exhaust for SCR NOx reduction. The control module monitors its electrical circuit and sets P2057 when the signal falls below the expected range, commonly due to a short to ground or a damaged connection.
Common causes
Most likely first.
- Short to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
How to diagnose it
- Record freeze-frame data and review live data for the Bank 2 Unit 2 valve command and any related reductant-system codes.
- Inspect the Bank 2 Unit 2 valve connector and harness for chafing, exposed conductors, moisture, or corrosion.
- Check the connector terminals for looseness, corrosion, and secure seating.
- Use the wiring diagram to test the valve control circuit for a short to ground, following the manufacturer's isolation procedure.
- If the harness is sound, test the valve and control circuit against the manufacturer's specification.
Common fixes
- Repair chafed wiring and protect it from rubbing again.
- Clean or repair corroded or loose connector terminals.
- Repair a control wire shorted to ground.
- Replace the Bank 2 Unit 2 reductant injection valve if it fails the specified test.
Can I keep driving?
You may be able to drive cautiously if there are no other symptoms, but the SCR system may not reduce NOx effectively. Watch for DEF/AdBlue warnings and a start countdown, which can lead to a no-start restriction if ignored.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.