P0428: Catalyst Temperature Sensor Circuit High Bank 1 Sensor 1
What to do
Usually driveable. If there is also a burning smell or a misfire, mention it — a genuinely overheating converter is a different and more urgent problem than a faulty sensor.
What this code means
The bank 1 catalyst temperature sensor signal is above its plausible range — the mirror of the low-input fault, and usually an open circuit or a signal wire that has found a voltage supply.
Worth distinguishing from a genuine over-temperature condition. If the reading is high but within the sensor's real range and the exhaust is genuinely hot, the fault may be upstream: a misfire or a badly rich mixture really can overheat a converter, and treating that as a sensor fault misses something that will destroy the converter.
Likely causes
Start here
- Faulty catalyst temperature sensor · moderate
- Open circuit in sensor wiring · moderate
Less common
- Signal wire shorted to voltage · moderate
- Genuine converter over-temperature from misfire or rich running · moderate
- Corroded or loose connector · easy
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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- The car — make, model, year and engine. The same fault behaves differently on each.
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