P2053: second DEF metering valve open-circuit evidence

P2053 identifies the second DEF metering valve's open-circuit monitor in the reviewed GM source. The dictionary's bank 1, unit 2 wording corresponds here to the hardware channel named DEFMV2. It should not be redirected to the first valve simply because another injector code looks similar.

The monitor checks the electrical path

The hardware interface must report an open-circuit fault and must not be indeterminate. No delivered-fluid amount, spray pattern or NOx-conversion threshold is part of this row's malfunction criterion. Poor dosing performance and an electrical open can be related in a real diagnosis, but this page establishes only the latter evidence.

The test can operate at key-on or with the engine running. It excludes cranking and requires battery voltage greater than 11 volts, together with calibration enablement. This creates a defined opportunity for electrical verification without assuming that a full emissions drive cycle has occurred.

What a completed check should show

Fault qualification needs 30 failing samples out of 60, using 100-millisecond updates, with Type A reporting over one trip. A passing verification requires a determinate unit 2 open-load result under those conditions; simply seeing the code absent while the test is inhibited is insufficient.

The source does not provide a resistance limit, connector assignment or instruction to replace the valve. Confirm the actual two-valve arrangement and use vehicle-specific circuit diagnosis before choosing a component. These details are limited to the documented 2025 GM monitor, not all vehicles carrying P2053.

Source: GM monitor, PDF page 777.