P2437 indicates that the secondary air injection (SAI) system air-flow/pressure sensor on bank 2 is reporting a signal voltage lower than the expected range. The engine control module uses this sensor to monitor SAI pressure, and a persistently low reading usually points to an electrical fault in the sensor circuit rather than a catalyst or engine mechanical problem.
The sensor itself can fail internally, causing the signal voltage to pull low or read below the calibrated threshold even when wiring is intact.
The wire between the sensor and the PCM may be chafed, pinched, or melted, shorting the signal line to ground and producing a near-zero voltage reading.
Corroded terminals, pushed-pin connector damage, or a poor ground can lower the signal voltage or disrupt the 5 V reference, triggering a circuit-low code.
If the PCM's 5 V reference or sensor ground circuit is open, shorted, or loaded down, the sensor cannot output a valid signal and the circuit reads low.
A blocked, kinked, or leaking SAI hose can prevent the sensor from seeing normal pressure; while this more often sets performance codes, severe low pressure can contribute to a circuit-low condition on some calibrations.
A rare internal PCM failure can misread a valid sensor signal as low, but this should only be considered after the sensor and all wiring are proven good.
Usually yes for normal driving, but the SAI system may not function correctly during cold starts, emissions can increase, and the vehicle may fail an emissions test.
Bank 2 is the side opposite cylinder 1; the exact location depends on engine layout. Service information for the specific engine is the most reliable way to identify it.
Almost never. P2437 is most commonly caused by a failed sensor or wiring fault. The PCM should only be suspected after the sensor, connector, and entire circuit have been thoroughly tested and ruled out.
A failed pump is more likely to set an airflow/pressure performance code, but if it causes pressure to read far below expected thresholds, it can contribute. Check the pump and hoses if the electrical side tests normal.