P201B: swirl-motor supply is low despite a valid relay supply

P201B is a supply-voltage diagnostic for the intake-runner swirl motor. The reviewed GM row compares hardware-reported system supply with a 6-volt lower boundary. It is not a direct position-error or mechanical-sticking test.

Two voltage conditions serve different purposes

The malfunction criterion is supply below 6 volts. Separately, the powertrain-relay supply must be above 11 volts for the diagnostic to run. These numbers are not contradictory limits on one generic battery measurement: one describes the monitored low-supply condition, while the other qualifies the environment in which the controller judges it.

This distinction matters when interpreting a low-battery event. A voltage capture that fails the relay-supply prerequisite does not reproduce the enabled P201B check. The hardware error status must also be determinate, and the system must be outside cranking.

What confirms the outcome

Calibration enablement is required. The fault counter calls for 240 failures within 300 samples at a 12.5-millisecond function rate, with Type B reporting across two trips. The counter indicates repeated low-supply evidence rather than a component identity.

For verification, establish that the relay prerequisite is satisfied and the hardware supply diagnostic runs without the qualifying low condition. A flap that moves once is not proof that the monitored supply stayed acceptable throughout the test. The source does not identify an exact fuse, connector or replacement component. Its numerical criteria remain specific to the published 2025 GM monitor until the vehicle's circuit and calibration are confirmed.

Source: GM monitor, PDF page 1388.