P2059: Reductant Injection Air Pump Control Circuit/Open

The air that atomizes DEF in an air-assisted system comes either from a small dedicated compressor or from an existing compressed-air system through a supply valve. P2059 concerns the driver circuit of that pump or valve, above all an open circuit: the output is switched on but no current flows. Deutz uses the code on its EMR L1 controller for the air pump or air supply valve (SPN 5796) with several failure types: -00 open circuit, -19 critically high output current, -31 load shorted and -2A unspecified electrical fault, while P2060 and P2061 cover high-side shorts to ground and battery. A blown fuse, a broken coil, an unplugged valve or corroded pins are typical. Without atomizing air the controller cannot dose DEF and NOx rises.

Medium severity. Can I keep driving?Deal with it soon. If the instrument cluster shows a countdown, the car may not restart once it reaches zero.

Symptoms

Emission warning lamp on
No DEF dosing, NOx rises
Power derate on trucks and machines

Most likely causes

Open coil in the air valve or pump motor
Connector unplugged or corroded, wire broken
Fuse or relay in the supply path failed
Shorted valve coil causing overcurrent shutdown

What to check, in order

Start with the simplest. You can tick off each step.

Check the AdBlue/DEF level and quality, and do not add additives or water
Check the continuity of the wire between the component and the control module.
Look for white crystals around the injector and the tank
Check connectors and heaters with the scanner
Run the dosing test available on your diagnostic tool
Replace parts only when the test points to that component

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P2059 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
0: Subsystem depends on the code range
59: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2059?

Deal with it soon. If the instrument cluster shows a countdown, the car may not restart once it reaches zero.

What causes code P2059?

The most common causes are: open coil in the air valve or pump motor; connector unplugged or corroded, wire broken; fuse or relay in the supply path failed.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.