P0544: Exhaust Gas Temperature Sensor Circuit — Bank 1 Sensor 1
What to do
Driveable at first, but do not leave it on a diesel. Regeneration is usually inhibited while this fault is present, so the particulate filter fills up in the background and the eventual repair is far more expensive than the sensor. If you mostly do short journeys, treat it as more urgent still.
What this code means
A circuit fault on the first exhaust gas temperature sensor on bank 1. On a diesel these sensors are what make particulate filter regeneration possible and safe: regeneration works by burning accumulated soot at around 600°C, and the module needs to know it has reached that temperature and has not exceeded it.
The consequence of a sensor the module cannot trust is that regeneration is inhibited entirely. The filter then fills, back pressure rises, and the vehicle eventually derates — a chain that begins with a cheap sensor and ends with a filter that needs specialist cleaning or replacement. That is why this code deserves prompt attention despite having no immediate symptom.
Likely causes
Start here
- Faulty exhaust gas temperature sensor · moderate
- Damaged wiring harness near exhaust heat · moderate
- Corroded or loose connector · easy
Less common
- Broken wire in control circuit · moderate
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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