P0548Generic code

P0548 Code: Exhaust Gas Temperature Sensor Circuit Low (Bank 2)

The P0548 code means the exhaust gas temperature sensor signal (bank 2, sensor 1) is below its minimum value. The main effect is reduced exhaust protection. It usually comes from the signal wire shorted to ground or from a missing reference voltage.

Severity
Medium
Can I keep driving?
Yes, but with caution
Estimated cost
$60 to $400
Difficulty
Medium
System
Emissions Control
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0548 code means

This sensor does the same job as the bank 1 sensor, but on the side opposite cylinder 1 on V engines, or as a second measuring point on some diesels.

The sensor changes its resistance with temperature, and the computer reads the resulting voltage. A low signal, which is what the P0548 code reports, is usually caused by the signal wire shorting to ground or by a missing reference.

Without the signal, the computer cannot protect that side of the exhaust or control the regeneration properly. The sensor profile pages explain how to test one.

To confirm it, unplug the component with the key on and watch what happens to the reading or the code. If the value jumps to the opposite extreme, the wiring is fine and the component is the one pulling the signal to ground. If nothing changes, look for the short in the wire, starting where the harness rubs against the engine, the chassis or the exhaust.

P0548 code symptoms

  • Check engine light on.
  • Reduced exhaust protection.

Likely causes of the P0548 code

  1. Signal wire shorted to ground. The harness rubs against the engine, the chassis or a bracket.
  2. Reference supply shorted. If several sensors fail at once, suspect the shared reference.
  3. Damaged sensor with an internal short.
  4. Connector with water or corrosion. It creates a path to ground.

How to diagnose the P0548 code step by step

  1. Read the sensor value on the scan tool and compare it with what you expect.
  2. Inspect the connector for corrosion, water or loose pins.
  3. Check the supply and ground with the key on: the reference should be correct, with less than 0.1 V of voltage drop on the ground.
  4. Measure the signal with the connector plugged in and watch whether it changes with the condition.
  5. Do a wiggle test on the harness with the scan tool in graph mode.
  6. Check the continuity of each wire to the computer (under 1 ohm).

How to fix the P0548 code

  • Repair the connector or the wiring.
  • Replace the sensor if the tests confirm it is bad.
  • Correct the real condition if there is one.
  • Clear the codes and verify with a road test.

Technical reference data

  • PT200 platinum resistance element or thermocouple.
  • These values are a general guide: check the manufacturer data for your vehicle.

Brand-specific notes

Bank 2 codes show up on V6 and V8 diesels, which have an exhaust sensor on each side of the engine.

P0548 on Ford

Shows up on Ford V6 and V8 diesels.

P0548 on Mercedes

Shows up on Mercedes V6 and V8 diesels.

P0548 on BMW

Shows up on BMW V6 and V8 diesels.

Frequently asked questions about P0548

What does the P0548 code mean?
It is a generic OBD2 code that means the exhaust gas temperature sensor signal on bank 2, sensor 1 is below its minimum value. In practice that points to a signal wire shorted to ground or a missing reference.
Can I drive with a P0548 code?
Yes, with some caution. The vehicle drives, but the computer cannot protect that side of the exhaust properly, so get it checked soon.
Do I have to replace the sensor?
Only if the tests confirm it. The connector and the wiring fail just as often.
What does the bank 2 EGT sensor do?
It does the same job as the bank 1 sensor, but on the side opposite cylinder 1 on V engines, or as a second measuring point on some diesels.
How much does it cost to fix P0548?
As a rough guide, between $60 and $400. A wiring or connector repair is at the low end, and a new sensor with labor is at the high end.
Will a P0548 code clear itself?
Only if the short was temporary, for example water in the connector that dried out. A wire rubbing on metal will bring the P0548 code back.
What is the most common cause of P0548?
A signal wire shorted to ground, usually where the harness rubs against the engine, the chassis or a bracket. A short in the shared reference supply and a damaged sensor follow.

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