What it means
Exhaust Gas Temperature Sensor Circuit Low Bank 2 Sensor 1: the signal voltage is below the expected range. The ECU uses this temperature to protect the catalyst and diesel particulate filter.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 2 Sensor 1 measures exhaust gas temperature at the first monitored position on the Bank 2 exhaust side. P0548 sets when its signal is below the expected range, often because the signal wire is shorted to ground or the sensor circuit has a poor connection.
Common causes
Most likely first.
- Signal shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check-engine light on
- Possible reduced engine power or altered exhaust-system operation
How to diagnose it
- Save freeze-frame data and check whether Bank 2 Sensor 1 live temperature is implausibly low compared with other exhaust readings.
- With the exhaust cool, inspect the Bank 2 Sensor 1 harness for chafing or crushed insulation that could let the signal wire touch ground.
- Check the connector for corrosion, loose pins, or moisture that could disrupt the Bank 2 Sensor 1 signal.
- Use the vehicle wiring diagram to test the signal circuit for a short to ground, then test the sensor according to the manufacturer's procedure.
- After repair, clear the code and verify that the Bank 2 Sensor 1 reading responds plausibly as the exhaust warms.
Common fixes
- Repair chafed Bank 2 Sensor 1 wiring that is shorted to ground.
- Clean or repair corroded or loose connector terminals.
- Replace the Bank 2 Sensor 1 exhaust temperature sensor if it fails testing.
- Repair a damaged circuit connection found during diagnosis.
Can I keep driving?
Limit driving if power is reduced or exhaust operation has changed, and avoid heavy loads until the signal is reliable. The module may not be able to use Bank 2 Sensor 1 data to manage exhaust temperature protection or aftertreatment.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.