P0545: Exhaust Gas Temperature Sensor Circuit Low (Bank 1 Sensor 1)

P0545 means the engine computer is seeing a voltage from exhaust gas temperature sensor 1 on bank 1 that is lower than the circuit can normally produce, which usually points to a wire shorted to ground, a damaged connector or a failed sensor rather than a real temperature problem. On most diesels sensor 1 is the first temperature sensor in the exhaust, often in the exhaust manifold before the turbo, and the engine uses it to protect the turbo from overheating and to manage particulate filter regeneration. Some petrol engines also have one, ahead of the catalytic converter. The sensor numbering is set by each manufacturer, so check which physical sensor is number 1 on your engine.

P0545 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0545 and illuminates the check engine light.

If your vehicle has triggered P0545, you may notice one or more of these symptoms:

• Check engine light on
• Often no change in how the car drives at first
• Glow plug light flashing on some diesels, VW group TDIs among them
• Reduced power or limp mode on some models
• Particulate filter regeneration not taking place, so a DPF warning can follow later
• P0544 or P0546 (other faults on the same sensor) stored alongside on some cars

Here are the most common causes of P0545:

Generally yes, for short-term driving. Driveable in the short term, and the car often feels normal at first. Do not leave it for weeks: without a trustworthy temperature signal from the first exhaust sensor, the engine computer may limit power to protect the turbo and may suspend particulate filter regeneration. A filter that goes too long without regenerating can block, which turns a sensor or wiring repair into a DPF clean or replacement.

Follow these steps to pinpoint the root cause of P0545:

1. Read all stored codes and the freeze frame with an OBD2 reader. Note any other codes for the same sensor (P0544 or P0546) and any particulate filter codes such as P2463 or P244B. A generic OBD2 reader shows the codes, the freeze frame and standard live data, and a few engines report exhaust gas temperature on a standard PID. On most cars the individual sensor readings, the soot load and the regeneration status need manufacturer-level software, and only that software or a workshop can run a forced regeneration.
2. Find out which physical sensor is number 1 on your engine. On many diesels it sits in the exhaust manifold just before the turbo, but engines with several exhaust temperature sensors number them differently, so check the workshop information before buying a part.
3. Unplug the sensor and inspect the connector for water, corrosion and pushed-back pins. Follow the lead along the exhaust and turbo and look for melted or chafed insulation where it could touch metal.
4. On most engines, unplugging the sensor with the key on should make the reading jump to the other end of the scale or set a circuit high fault instead. If it does, the wiring back to the engine computer is probably fine and the sensor is the likely fault.
5. Measure the sensor's resistance against the manufacturer's specification, then check the signal wire for a short to ground and for continuity back to the engine computer.
6. Replace the sensor if it is out of specification, using the correct part for the engine code and position. A sensor that has been in the exhaust for years is often seized, so penetrating oil and heat may be needed, and a buried sensor 1 can mean removing heat shields.
7. Clear the code and road-test. If the filter loaded up while the sensor was faulty and the car does not regenerate on its own, a forced regeneration with manufacturer-level software may be needed.

Repair costs for P0545 vary depending on the root cause and your vehicle. Here are typical estimates:

P0545 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

These codes are often seen alongside P0545 or indicate related issues: