What it means
Reductant Injection Valve Circuit High (Bank 1 Unit 1): the signal voltage is above 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 1 Unit 1 meters DEF into the exhaust for SCR NOx reduction. P2049 sets when the control module detects voltage above the expected range in that valve circuit, which can result from a short to battery voltage or another circuit fault.
Common causes
Most likely first.
- Short to B+
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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
- Check freeze-frame data and related reductant dosing or NOx codes to determine when the Bank 1 Unit 1 circuit voltage went high.
- Inspect the Bank 1 Unit 1 valve connector and harness for damaged insulation, corrosion, loose terminals, or wiring pinched against a power source.
- Check the valve circuit for a short to battery voltage using the manufacturer's wiring information.
- Test circuit voltage and continuity, then test the valve solenoid winding against the manufacturer's specification.
- After repairing the cause, clear the code and verify that Bank 1 Unit 1 valve circuit readings return to the expected range.
Common fixes
- Repair wiring shorted to battery voltage near the Bank 1 Unit 1 valve.
- Repair a loose or corroded valve connector terminal.
- Replace the Bank 1 Unit 1 injection valve if it causes the high circuit reading and the wiring is sound.
Can I keep driving?
Reduce driving and address an active DEF or NOx warning promptly, especially if a no-start countdown is shown. The circuit fault can disrupt Bank 1 Unit 1 dosing, raising emissions and potentially leading to an inspection failure or a no-start condition.
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.