What it means
Catalyst temperature sensor at bank 2 sensor 1 below lower plausibility — short to ground. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 2 Sensor 1 measures catalyst temperature and sends a signal to the control module. P0437 sets when that circuit signal is lower than the module's plausible range, commonly because the signal is shorted to ground or the connection is faulty.
Common causes
Most likely first.
- Short to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
How to diagnose it
- Check freeze-frame and live data for Bank 2 Sensor 1 to confirm the low reading is present and note whether it changes when the harness moves.
- Inspect the Bank 2 Sensor 1 harness along its route for chafing, melted insulation, water intrusion, or pinched sections that could short the signal to ground.
- Check the sensor connector for corrosion, pushed-back pins, poor terminal fit, and damaged seals.
- With the manufacturer's wiring diagram, test the Bank 2 Sensor 1 signal circuit for a short to ground and check its supply and ground paths as applicable.
- If the wiring and connector pass, test Bank 2 Sensor 1 against the manufacturer's specifications before considering a control-module fault.
Common fixes
- Repair chafed or pinched wiring shorting the Bank 2 Sensor 1 signal to ground.
- Clean or replace corroded terminals and restore a proper connector seal.
- Secure pushed-back pins and repair poor terminal contact.
- Replace Bank 2 Sensor 1 if it fails testing with a sound circuit.
Can I keep driving?
Gentle driving is usually possible if the engine runs normally, but the module may not monitor Bank 2 catalyst temperature correctly and the vehicle may fail emissions inspection. Avoid heavy load if there is a strong sulfur smell, and repair the short or connection fault promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.