P2432: Low secondary-air pressure signal and why the voltage matters

P2432 identifies a low secondary-air pressure sensor signal. The GM 2009 Group 04 implementation checks circuit continuity through measured sensor voltage; it sets the low-side boundary below 0.498 V. This is an electrical input limit, not a specification for how much air the pump should deliver.

A pressure value can mislead

If the voltage is outside its accepted range, a scan tool may still display a pressure value calculated from it. That number cannot independently establish a blocked pipe, weak pump or closed valve. The controller has already questioned the input used to calculate pressure.

The same source assigns P2433 to the high or open-circuit side, above 4.501 V. This distinction is useful when reviewing intermittent evidence: a low-side event and a high-side event are different observations even though both involve the same sensing system. Neither code alone identifies which wire or component failed.

What constitutes a meaningful recheck

GM lists a continuous check, a 0.5-second primary enable interval and a 0.2-second fault criterion, with illumination after two driving cycles. These short electrical checks differ from a complete secondary-air flow test. A normal pump sound or one successful cold start therefore does not directly verify the recorded voltage fault.

A useful diagnostic record preserves the sensor voltage, reference-related faults and event state before relying on pressure-based conclusions. Confirm the actual vehicle calibration before applying this limit: another GM implementation can use a different low-voltage threshold for the same standardized code.

Source and applicability

GM 2009 09OBDG04 Engine Diagnostics, only the cited secondary-air monitor. The file does not establish the applicability of this code to a particular model or engine; thresholds are calibration-specific.

General Motors source, physical page 6