P2041 Reductant air pressure sensor: signal drops out at times ("A")

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

P2041 means: Reductant air pressure sensor: signal drops out at times ("A"). The AdBlue (SCR) system sprays a urea solution into the exhaust to reduce nitrogen oxides. Drive gently and have the car checked soon. The most common repair costs about €45–90 in Estonia, depending on make and model.

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 drops out now and then. The most common cause is a loose connector or a chafed wire.

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 · Wiring or connector repair €45–90
2. 2Wire broken or chafed · Wiring or connector repair €45–90
3. 3Faulty sensor or dosing module · Sensor replacement €80–160
4. 4Engine computer fault (rare) · Control unit check and software €150–300

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 Air Pressure Sensor "A" Circuit Intermittent