Faulty exhaust gas temperature sensor, internally shorted or drifted low; Sensor signal wire chafed and shorted to ground or to the sensor ground wire; Corroded, wet or damaged sensor connector causing a low signal; Heat damage to wiring or loom near the exhaust; Exhaust leak near the sensor affecting the reading or damaging the sensor; Fault inside the control unit or its sensor supply circuit.

P0548

Exhaust Gas Temperature Sensor Circuit Low Bank 2 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
48: FaultThe specific fault in that area

What it means

P0548 is the generic code for the Bank 2 Sensor 1 exhaust gas temperature (EGT) sensor circuit reading low. The control unit saw a signal voltage lower than the expected range, usually because of a short to ground, a wiring fault or a failed sensor. Bank 2 is the side of the engine opposite cylinder number one, and Sensor 1 is normally the upstream position. Sensor position and layout vary by engine, so confirm this on the specific model.

Symptoms

Engine warning light on
Reduced power or limp mode on some vehicles
Particulate filter regeneration not carried out or carried out poorly
Higher than normal fuel consumption
Other exhaust temperature or filter-related codes stored alongside

Possible causes

Faulty exhaust gas temperature sensor, internally shorted or drifted lowlikely
Sensor signal wire chafed and shorted to ground or to the sensor ground wirelikely
Corroded, wet or damaged sensor connector causing a low signalpossible
Heat damage to wiring or loom near the exhaustpossible
Exhaust leak near the sensor affecting the reading or damaging the sensorpossible
Fault inside the control unit or its sensor supply circuitrare

How to diagnose

Read all stored and pending codes and note freeze frame data, including engine load, coolant temperature and exhaust temperature at the time of setting.
Check the live exhaust gas temperature data for Bank 2 Sensor 1 on a cold engine and compare it with ambient or other exhaust sensor readings; a very low or implausible value points to the circuit or sensor.
Inspect the sensor, its wiring and the connector for chafing, heat damage, corrosion, water ingress and bent or pushed-out pins.
Check for exhaust leaks around the sensor and the manifold or turbocharger joints.
Using the manufacturer's wiring diagram, test the sensor supply, signal and ground circuits for shorts to ground and for continuity.
Measure the sensor resistance at the connector and compare it with the manufacturer's specification at a known temperature.
Wiggle the harness with the engine running while watching live data to find intermittent faults.
If the wiring and sensor test fine, check the control unit connector and supply, following model-specific procedures.

How to fix

Replace the Bank 2 Sensor 1 exhaust gas temperature sensor if it is out of specification.
Repair or replace damaged wiring, and secure and protect the loom away from heat sources.
Clean or replace corroded or damaged connector terminals and seal out moisture.
Repair any exhaust leak near the sensor.
Clear the code after repair and road test to confirm it does not return; if the control unit is suspected, have it diagnosed to manufacturer procedure.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but fix it soon because the control unit may not be able to protect the turbocharger or exhaust filter, and regeneration may be affected. If the car goes into limp mode or shows other warnings, limit driving.

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