OBD-II code family
Catalyst Temperature Sensor Faults (8 codes)
8 related fault descriptions. Use each full code and the exact vehicle service information to identify its circuit, monitored condition, and required tests.
Codes in this family
This is the complete published member list for this guide. Each code retains its own page; shared diagnostic context does not mean that every member has the same test or repair.
- P0425Catalyst Temperature Sensor (Bank 1)
- P0426Catalyst Temperature Sensor Range/Performance (Bank 1)
- P0427Catalyst Temperature Sensor Low Input (Bank 1)
- P0428Catalyst Temperature Sensor High Input (Bank 1)
- P0435Catalyst Temperature Sensor (Bank 2)
- P0436Catalyst Temperature Sensor Range/Performance (Bank 2)
- P0437Catalyst Temperature Sensor Low Input (Bank 2)
- P0438Catalyst Temperature Sensor High Input (Bank 2)
What these codes mean
P0425/P0435 identify the catalyst-temperature sensor inputs for banks1/2. P0426/P0436 distinguish range/performance; P0427/P0437 identify low input and P0428/P0438 high input. These are sensing conditions, different from catalyst efficiency, heated-catalyst temperature below threshold and catalyst-heater control.
Actual temperature, an electrical input and a scan tool’s converted or substitute display are different things. Low does not universally mean hot or cold, and high does not by itself prove overheating or an open sensor. Identify the sensor design, terminal functions, expected values and any failure-type suffix before interpreting measurements.
A believable number does not certify wiring or sensor accuracy. Range/performance can require response and reference checks as well as circuit investigation. Comparing banks can be useful only under an approved comparison: different locations or operating conditions can create genuine differences, and a normal reading on one bank does not prove the other circuit’s supplies or return are sound.
Use the exact diagram to locate the component. A temperature parameter on a generic scan tool can be calculated rather than supplied by a sensor at that apparent location. Inspect cooled wiring and connectors, then have the specified isolated sensor, signal and return checks performed. Do not bridge terminals, feed battery voltage into the circuit or use a jumper response as complete proof of a failed sensor.
Repair the demonstrated circuit or component fault and verify the relevant data and monitor. Do not quote a converter solely from these codes or presume that the absence of an efficiency code proves it healthy. Costs depend on the actual sensor, harness, access and diagnosis.
Identify the circuit on your vehicle
Match the full DTC, reporting module, and any failure-type suffix to the service information for your exact year, make, model, engine, and equipment. An identifier alone does not establish installed hardware count, location, connector pinout, or a universal measurement.
Where the manufacturer publishes its own meaning for this code, that is the one to work from — it describes the actual component on your vehicle, which the generic definition cannot. Keep the generic description for what it is good for: it tells you which subject area the standard assigned the code to, which is useful context when the two appear to disagree. If they do disagree, follow the manufacturer.