P0425 to P0429 and P0435 to P0439: catalyst temperature sensors and heaters
The temperature sensor of the catalytic converter on bank 1 (P0425 to P0428) or bank 2 (P0435 to P0438) has a circuit fault or an implausible, low or high reading, or the catalyst heater control circuit (P0429, P0439) has a fault.
SeverityModerateUsually not urgent today, but it can get worse if left.
Can you keep driving?Drive gently, check it soonWhat does P0425 mean?
Some engines measure the temperature in or near the catalytic converter, to protect it from overheating and, on diesels, to manage the particulate filter and other after-treatment. A few have an electrically heated catalyst that warms up faster after a cold start. If a sensor fails, the computer uses a model instead and may limit regeneration or power to stay safe. The sensors sit in very hot spots, so heat damage to their wiring is common.
What causes P0425?
- A failed temperature sensor, worn out by heat
- Heat damage to the sensor's wiring or connector
- A connector corroded by road spray under the car
- A failed catalyst heater or its relay
What to check first for P0425
- Inspect the sensor's wiring along the exhaust for melted insulation
- Compare the temperature readings on a scan tool with the engine cold, where they should be close to outside temperature
- Look for other exhaust codes, such as particulate filter or oxygen sensor codes
- Check the catalyst heater relay and fuse where fitted
Can you drive with P0425?
Usually you can drive to a workshop. If the engine also feels weak, smells hot or the exhaust glows, stop, because the catalytic converter may be overheating.
Clear a code only after the fault is fixed. A code that comes back means the cause is still there, and a warning light left on can hide a second fault behind the first.
Codes on this page
10
- P0425Catalyst Temperature Sensor
- P0426Catalyst Temperature Sensor Range/Performance
- P0427Catalyst Temperature Sensor Low
- P0428Catalyst Temperature Sensor High
- P0429Catalyst Heater Control Circuit
- P0435Catalyst Temperature Sensor
- P0436Catalyst Temperature Sensor Range/Performance
- P0437Catalyst Temperature Sensor Low
- P0438Catalyst Temperature Sensor High
- P0439Catalyst Heater Control Circuit
Related codes
Checked on · Rafael Soares
These are the generic meanings every manufacturer shares. Each brand adds its own detail, so your car's handbook, its service information and a qualified mechanic have the last word. OdoKeep has no connection with any manufacturer, and the app does not read codes from the car.
