What it means
Catalyst temperature sensor at bank 1 sensor 2 above upper plausibility — open signal or short to B+.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The bank 1 sensor 2 catalyst temperature sensor measures temperature at the downstream position on bank 1. P042D means the control module sees a signal above the expected range, often from an open signal wire or a short to battery voltage, so it cannot trust the temperature reading.
Common causes
Most likely first.
- Open signal line
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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
- Save freeze-frame data and check whether the bank 1 sensor 2 PID is pinned high or implausible under the recorded conditions.
- Inspect the downstream sensor connector for corrosion, loose contacts, or a terminal pushed back into the connector body.
- Follow the harness for a break, heat damage, or a pinched section that could touch a powered wire.
- Test for an open in the signal circuit and unintended voltage on the signal wire using the manufacturer's wiring information and specification.
- If the wiring is sound, test the sensor and then the control-module circuit before replacing either.
Common fixes
- Reconnect the sensor plug and correct loose or damaged terminals.
- Repair an open signal wire or wiring shorted to a power source.
- Replace a corroded connector or damaged harness section.
- Replace the bank 1 sensor 2 temperature sensor if it fails specification with sound wiring.
Can I keep driving?
Gentle, limited driving is generally possible if the vehicle runs normally, but avoid heavy loads if it loses power or develops a sulfur smell. The fault can impair emissions monitoring and cause an inspection failure.
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.