P2056: Reductant Injection Valve Circuit/Open (Bank 2 Unit 2)

What it means

Reductant Injection Valve Circuit/Open (Bank 2 Unit 2): the 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 valve for Bank 2, Unit 2 meters DEF/AdBlue into the exhaust for SCR NOx reduction. The control module monitors the valve circuit and sets P2056 when it detects an open circuit, such as a broken connection or an open valve winding.

Common causes

Most likely first.

1. Solenoid winding open
2. Pin pushed back out of connector body
3. 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

1. Save freeze-frame data and check live reductant-system data for the Bank 2 Unit 2 valve command and related faults.
2. Inspect the Bank 2 Unit 2 valve connector and harness for a disconnected plug, damaged wiring, or a terminal pushed back into the connector.
3. Check that each connector terminal is seated and makes sound contact, looking for corrosion or looseness.
4. With power isolated as specified by the manufacturer, test the valve winding and circuit continuity using the wiring diagram.
5. If the external circuit is intact, test the valve and control-module output according to the manufacturer's procedure.

Common fixes

• Reconnect the valve plug or reseat a pushed-back terminal.
• Clean or repair corroded connector contacts.
• Repair a broken or open circuit wire.
• Replace the Bank 2 Unit 2 valve if its winding is open to specification.
• Repair the affected module connection if testing confirms an internal open.

Can I keep driving?

If the vehicle runs normally, a short trip may be possible, but the SCR system may not dose reductant and NOx emissions can rise. Take any DEF/AdBlue warning or start countdown seriously, since continued use may eventually trigger a no-start restriction.