P2055 Reductant injector: signal or voltage too high (unit 2, bank 1)

By: Diagno editorial team · Updated: 2026-10-15

P2055 means: Reductant injector: signal or voltage too high (unit 2, bank 1). The AdBlue (SCR) system sprays a urea solution into the exhaust to reduce nitrogen oxides. Drive gently and have the car checked soon. The repair usually costs about €60–400 in Estonia. The most common cause: connector loose, damp or corroded.

What it means

The AdBlue (SCR) system sprays a urea solution into the exhaust to reduce nitrogen oxides. The computer found a fault in the AdBlue quantity, quality, pump, injector or NOx sensor. The signal voltage is too high. Usually a wire is shorted to power, the ground is broken or the part itself has failed.

What you may notice

• AdBlue warning on the dashboard
• A countdown of km left before the car won't restart
• Engine light on

What could be wrong

1. 1Connector loose, damp or corroded
2. 2Wire shorted to power or ground broken
3. 3Faulty sensor or dosing module
4. 4Engine computer fault (rare)

Repair difficulty: Moderate

What you can check yourself

First look at the connector and wiring: anything loose, melted or green with corrosion? Check the AdBlue level and only fill with certified AdBlue. Don't ignore the warning: eventually the car won't start. You can check the simple things yourself, but the repair is best done in a workshop.

How we fix it

1. We read the fault data on the diagnostic tool and check whether the fault is constant
2. We measure the circuit's supply, ground and signal
3. We repair the wire or replace the connector
4. If the wiring is fine, we replace the sensor or dosing module

Standard SAE description: Reductant Injection Valve Circuit High Bank 1 Unit 2