P2437: Bank 2 AIR pressure low voltage relative to its reference

In the cited GM dual-bank secondary-air system, P2437 records a Bank 2 pressure sensor signal below 5% of its 5 V reference. The comparison is expressed as a fraction of the reference, not as an independent measurement of AIR pressure or pump output.

Why the reference is part of the diagnosis

A low pressure value on a scan tool may reflect this low electrical input. It should not immediately be interpreted as proof of a pump that cannot move air. The source lists controller processor and 5 V reference fault groups among conditions that disable this monitor, showing that trustworthy supply and processing information matters to the result.

For that reason, preserve reference-related codes and their order alongside P2437. Multiple affected inputs and an isolated Bank 2 signal do not present the same diagnostic picture. The table does not identify a failed connector pin or authorize replacing the pressure sensor on the code alone.

The fault is sampled, not instantaneous

GM specifies 800 failing samples out of 1,000, using a 6.25-millisecond loop. This is a sampled electrical-range check, with a two-trip Type B illumination strategy. One normal reading taken afterward cannot reconstruct the sampled interval that produced the fault.

The paired P2438 monitor checks the upper electrical boundary. P2435 and P2436 evaluate response and plausibility instead. Verification should first establish valid electrical input under the applicable vehicle procedure, then interpret any separate airflow or pressure-performance results. Bank 2 location and the exact circuit arrangement remain vehicle-specific.

Source and applicability

GM 2009 09OBDG11 Engine Diagnostics, Dual Bank section, only the cited secondary-air monitor. Physical bank location and per-code vehicle applicability require vehicle-specific service information.

General Motors source, physical page 147 · General Motors source, physical page 148