P0428
Catalyst Temperature Sensor Circuit High Bank 1 Sensor 1
Catalyst / emissions
Generic OBD-II
Medium
What it means
P0428 means the catalyst temperature sensor on bank 1 (sensor 1) is reading abnormally high — usually an open circuit or a signal above its normal range. This sensor lets the ECM monitor catalytic-converter temperature. It's a sensor-circuit fault: the problem is normally the sensor or its wiring, not the converter itself.
Medium
Can I keep driving? Driveable — this is a catalyst monitoring sensor, so the car runs normally; expect a warning light and a possible emissions-test failure rather than a breakdown.
Common symptoms
What you'll notice
- Check-engine light on
- Likely failed emissions test
- Little or no change in driveability
- Catalyst monitor may not complete readiness
Common causes
Most likely first
- Faulty catalyst temperature sensorLikely
- Open circuit or short to voltage in the sensor wiringCommon
- Loose or corroded connectorCommon
- Faulty ECM (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and note the sensor's reported temperature.
- Inspect the sensor connector and wiring for opens or shorts to power.
- Measure the sensor's resistance and compare it to its temperature spec.
- Replace the catalyst temperature sensor if it reads out of range.
- Only investigate the converter itself once the sensor circuit is confirmed good. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0428?+
Yes — it's a monitoring-sensor fault, not a driving hazard, though it may fail emissions and won't complete the catalyst monitor.
Can I just clear P0428?+
It returns once the ECM rechecks the circuit; repair the sensor or wiring first — don't replace the converter on this code alone.
Related codes
Often seen with P0428
Read & clear P0428 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX