What it means
Reductant Injection Valve Circuit Low (Bank 1 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 Bank 1 Unit 2 reductant injection valve doses DEF/AdBlue into the exhaust under SCR control. P2054 sets when the module sees a circuit signal below its expected range, indicating a possible short to ground or an electrical fault affecting this valve's circuit.
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
- Review freeze-frame data and check the Bank 1 Unit 2 circuit during a supported actuator test to confirm the low signal.
- Inspect the Unit 2 injector connector and nearby harness for corrosion, moisture, chafing, loose pins, or contact with ground.
- Test the control and supply wiring for a short to ground and check terminal voltage and continuity against the manufacturer's specification.
- Test the Bank 1 Unit 2 valve winding using the specified method to determine whether the injector has an internal electrical fault.
- If the injector and harness test correctly, check the control module driver circuit following vehicle service information.
- Repair the identified fault and verify normal circuit response with the actuator test.
Common fixes
- Restore a loose or corroded Bank 1 Unit 2 connector contact.
- Repair chafed wiring or a circuit wire shorted to ground.
- Replace the Bank 1 Unit 2 injector if its winding fails the specified test.
- Repair a confirmed module driver fault and verify the circuit under command.
Can I keep driving?
A short trip may be possible if the vehicle runs normally, but arrange diagnosis soon and heed any SCR warning or countdown. The faulty Unit 2 circuit can reduce NOx treatment and continued operation may lead to a restart restriction.
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.