What it means
Reductant Injection Air Pump Control Circuit/Open: the control circuit is open. 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 air pump supplies air used by some SCR systems to deliver or manage reductant dosing. The control module monitors the pump control circuit and sets P2059 when it detects an open circuit, such as a broken wire or open pump winding.
Common causes
Most likely first.
- Open winding or supply wire
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
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
- Save freeze-frame data and check live reductant-system data for the air-pump command and related faults.
- Inspect the air pump connector and harness for a disconnected plug, damaged wire, or a terminal pushed back in the connector.
- Check connector terminals for corrosion, looseness, and secure seating.
- With power isolated as specified by the manufacturer, test pump winding and circuit continuity using the vehicle wiring diagram.
- If the wiring is intact, test the pump and control-module output according to the manufacturer's procedure.
Common fixes
- Reconnect the pump plug or reseat a pushed-back terminal.
- Clean or repair corroded connector contacts.
- Repair a broken supply or control wire.
- Replace the reductant air pump if its winding or operation fails the specified test.
- Repair the module connection if testing confirms an internal open.
Can I keep driving?
A short drive may be possible if the vehicle runs normally, but reductant delivery or SCR operation may be impaired and NOx emissions can rise. Do not ignore DEF/AdBlue warnings or a start countdown, which may eventually prevent the vehicle from restarting.
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.