P0437 indicates the engine control module has detected a lower-than-expected voltage signal from the pre-catalyst temperature sensor on Bank 2. This electrical fault typically points to an internal sensor failure, a short to ground in the wiring, or a connection issue rather than a problem with the catalytic converter itself.
The thermistor or internal circuitry of Bank 2 Sensor 1 can degrade or short, causing the signal voltage to drop below the PCM threshold.
Chafing, melting, or pinching of the harness near hot exhaust components can create a path to ground that pulls the circuit voltage low.
Moisture, contamination, or bent terminals inside the sensor or inline connector can bridge circuits or increase resistance, producing a low signal.
Improperly routed wiring or exhaust modifications near the catalytic converter can physically damage the sensor or its pigtail.
An internal engine computer malfunction could theoretically misread a normal sensor voltage as low, but this is a genuinely rare cause.
Short trips are generally possible, but the check engine light will remain on. If the vehicle uses this sensor for over-temperature protection, continued driving may risk reduced power or catalyst damage.
No. This code indicates an electrical circuit problem with the temperature sensor itself, not catalyst efficiency failure. The converter is often mechanically fine.
Usually not. A failed PCM is an unlikely cause for this circuit-low code. Most cases are resolved by replacing the faulty sensor or repairing damaged wiring.
An exhaust leak will not typically cause a circuit-low electrical fault, though it can affect temperature readings. The root cause of P0437 is almost always an electrical issue with the sensor or its wiring.