What to do about a P0546 fault code
Leave P0546 too long and the DPF can stop regenerating, which turns a sensor fault into a soot problem. The code means the first exhaust temperature sensor's signal is reading too high, and we can test it where the vehicle is parked.
Can you keep using it with P0546?
Fine for now
If the car pulls normally and there's no DPF light, using it for a week or so is usually fine while you book a check.
Get it booked this week
A DPF light, the fan running on more than usual or regenerations stopping all mean soot is starting to build. Get the sensor sorted before the filter needs attention too.
Stop and call us
This rarely applies to P0546 on its own. Call us if the car goes into limp mode or the DPF light starts flashing.
Signs that go with P0546
- The engine management light, often with no change in performance
- A DPF light appearing a week or two later
- Limp mode on some vehicles
- The fault arriving after exhaust or turbo work
What P0546 means
The official definition is Exhaust gas temperature sensor circuit high (bank 1, sensor 1). The sensor's signal voltage is above the range a working sensor gives, which usually points to an open circuit, an unplugged connector or a failed sensor rather than a real temperature problem.
Common causes
An open circuit in the wiring
Heat from the exhaust can make wires brittle until one breaks, leaving the signal sitting high.
A connector that's come apart
Plugs near the exhaust can loosen or get left undone after other work.
A failed sensor
The sensor element can fail internally, especially after years of heat cycles.
What to do right now
- Check for a DPF light and note whether the fan has been running on.
- Think back to recent work. A sensor left unplugged after a turbo or exhaust job is a common culprit.
- Don't clear and forget it. The code returns, and meanwhile the DPF may not regenerate.
- Book a check with the full code and any others on the reader.
How we sort P0546 where the vehicle is parked
We read the codes, compare the sensor's figure with the other temperature readings and test the wiring and plug. A diagnostic is £100 + VAT, and a garage replaces the sensor if it has failed, with our findings to go on.
If regenerations have been missed and soot has built up, we can carry out DPF cleaning (£275 + VAT) on the same visit once the sensor is right. If the vehicle can't be moved, let us know when booking.
Reviews
Will P0546 put the car into limp mode?
Some vehicles cut power to protect the turbo when they can't trust the exhaust temperature reading. Others just light the warning.
How long can I leave P0546 before it gets worse?
A week or two is usually manageable. Beyond that, missed regenerations can leave the DPF heavily loaded.
Can P0546 damage the DPF?
Indirectly. Without a trusted temperature reading many vehicles stop regenerating, and a filter left to fill can block or crack later.
Will my car pass its MOT with P0546 showing?
Not with the engine light on, so get it sorted before the test.
Is P0546 something I can fix myself?
Checking the sensor plug is connected is worth doing if you can reach it safely with the exhaust cold. Testing the circuit needs a meter and live data. Its sister code is P0544.
Get P0546 looked at where the vehicle is parked
Tell us where the vehicle is and whether there's a DPF light on, and we'll come out and test the sensor.
More fault codes explained
Eccles, Manchester M30 0SF