What it means
The exhaust gas temperature sensor signal at bank 1, sensor 1 is below the lower diagnostic threshold. Indicates short to ground or sensor fault.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 1 Sensor 1 measures exhaust gas temperature at the first monitored position on the Bank 1 exhaust side. The control module sets P0545 when this sensor's signal falls below its lower diagnostic threshold, commonly because the signal wire is shorted to ground or the sensor has failed.
Common causes
Most likely first.
- EGT sensor internally faulty
- Signal wire shorted to ground
Symptoms
- Check-engine light on
- Possible reduced engine power or altered exhaust-system operation
How to diagnose it
- Save freeze-frame data and check the Bank 1 Sensor 1 live temperature reading for an implausibly low value.
- With the exhaust cool, inspect the Bank 1 Sensor 1 connector and harness for chafing, crushed insulation, corrosion, or a wire touching ground.
- Use the wiring diagram to check the sensor signal circuit for a short to ground and inspect its ground and connector terminals.
- Test the Bank 1 Sensor 1 sensor and circuit according to the manufacturer's procedure to determine whether the sensor or wiring is pulling the signal low.
- After repair, clear the code and confirm that the live temperature responds plausibly as the exhaust warms.
Common fixes
- Repair chafed or pinched Bank 1 Sensor 1 signal wiring that is shorted to ground.
- Clean or repair corroded connector terminals.
- Replace the Bank 1 Sensor 1 exhaust temperature sensor if it fails testing.
- Repair a damaged ground or signal-circuit connection identified during testing.
Can I keep driving?
If the engine runs normally, limit driving and avoid heavy loads until the fault is diagnosed, especially if power is reduced or exhaust operation changes. The module may not be able to use the Bank 1 Sensor 1 reading reliably to protect or manage the exhaust system.
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.