What it means
Catalyst temperature sensors 1 and 2 on bank 2 disagree by more than the allowed tolerance over a drive cycle.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Catalyst temperature sensors 1 and 2 monitor temperature at different points in the exhaust catalyst system on bank 2, the side opposite cylinder 1 on engines with two banks. The control module sets P046B when their readings disagree more than expected over a drive cycle, suggesting a drifting sensor, circuit fault, or exhaust leak on bank 2.
Common causes
Most likely first.
- One catalyst temperature sensor drifting or failing
- Open or short in a sensor circuit
- Corroded or loose sensor connector
- Exhaust leak affecting temperature readings
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
- Review freeze-frame data and compare bank 2 catalyst temperature sensor 1 and 2 live readings as the exhaust warms.
- Inspect both bank 2 sensor connectors and nearby wiring for corrosion, heat damage, loose terminals, or contact with the exhaust.
- Check the bank 2 exhaust joints around and between the sensor locations for leaks that could alter temperature readings.
- Test each bank 2 sensor circuit for opens or shorts and compare sensor response with the manufacturer's specification.
- If the sensors and circuits pass, investigate catalyst operation and exhaust conditions on bank 2 before replacing parts.
Common fixes
- Repair damaged or heat-affected wiring to a bank 2 catalyst temperature sensor.
- Clean or repair a loose or corroded connector at sensor 1 or sensor 2 on bank 2.
- Repair an exhaust leak affecting the bank 2 sensor readings.
- Replace the bank 2 sensor that fails its response or circuit checks.
Can I keep driving?
You can usually drive gently if there are no severe symptoms, but avoid hard acceleration and prolonged heavy loads until the temperature readings are checked. A catalyst or exhaust fault can worsen, raise emissions, or overheat exhaust components; stop if the exhaust glows or engine performance drops sharply.
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.