Faulty exhaust gas temperature sensor reading falsely low or internally shorted; Signal wire chafed or shorted to earth, often near hot exhaust components or sharp edges; Corroded, wet or damaged sensor connector causing low signal voltage; Heat-damaged wiring insulation allowing signal and earth wires to touch; Wiring fault between the sensor and the control unit, such as a short between circuits; Faulty engine control unit input circuit.

P0545

Exhaust Gas Temperature Sensor Circuit Low Bank 1 Sensor 1.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
5: AreaVehicle speed, idle control and auxiliary inputs
45: FaultThe specific fault in that area

What it means

P0545 means the engine control unit has seen a voltage from the Bank 1 Sensor 1 exhaust gas temperature sensor circuit that is lower than expected. This usually points to a short to earth in the signal wiring, a faulty sensor, or a wiring or connector problem. The sensor is normally fitted upstream of the catalyst or turbocharger, but its position varies by engine.

Symptoms

Engine management light on
Reduced engine power or limp mode on some engines
Turbocharger or catalyst protection strategies activating, which may limit performance
Poor fuel economy on engines that use exhaust temperature to adjust fuelling
Failed emissions test or particulate filter regeneration problems on diesels

Possible causes

Faulty exhaust gas temperature sensor reading falsely low or internally shortedlikely
Signal wire chafed or shorted to earth, often near hot exhaust components or sharp edgeslikely
Corroded, wet or damaged sensor connector causing low signal voltagepossible
Heat-damaged wiring insulation allowing signal and earth wires to touchpossible
Wiring fault between the sensor and the control unit, such as a short between circuitspossible
Faulty engine control unit input circuitrare

How to diagnose

Read the stored codes and freeze frame data to see engine load, temperature and conditions when the fault set, and check for other exhaust temperature or related codes.
Check live data for the Bank 1 Sensor 1 temperature reading with the engine cold; it should be close to ambient or coolant temperature, and an implausibly low or fixed value points to the circuit or sensor.
Inspect the sensor, its connector and the wiring along the exhaust for chafing, heat damage, water ingress and corrosion.
Unplug the sensor and check the live data again; the reading should change to a different fault state. If it does not, suspect a short to earth in the wiring.
Check the sensor wiring for continuity and for a short to earth, using the manufacturer's wiring diagram for the correct pins on that model.
Measure the sensor resistance against the manufacturer's specification, as values and sensor type vary by model and engine.
Check the reference voltage and earth at the control unit side of the connector, following model-specific procedures.
After repair, clear the code and road test while monitoring the temperature reading as the engine warms up.

How to fix

Replace the exhaust gas temperature sensor if it is faulty or out of specification.
Repair or replace damaged wiring and secure it clear of hot or sharp parts.
Clean or replace corroded or water-damaged connectors and terminals, and ensure seals are fitted correctly.
Repair the short between circuits in the harness following the wiring diagram.
Replace or repair the control unit only after the sensor, wiring and connector have been fully ruled out.

Can I keep driving?

Medium severity

The car can usually be driven short distances, but the control unit may reduce power or lose protection for the turbocharger or catalyst. Get it checked soon, and avoid heavy loads or sustained high speeds in the meantime.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.