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P2248 — O2 Sensor Reference Voltage Performance Bank 2 Sensor 1

Manufacturer-specificPowertrain (engine & transmission)

The P2248 code indicates that the powertrain control module (PCM) has detected a performance problem with the reference voltage circuit for the oxygen sensor on bank 2, sensor 1. This upstream sensor measures exhaust oxygen content to help control the air-fuel mixture, and a fault in its reference voltage can lead to inaccurate readings. The issue is typically caused by a faulty sensor, wiring problems, or rarely a PCM failure.

Symptoms

What causes it — most likely first

1. Faulty O2 sensor (Bank 2, Sensor 1)

The sensor itself may have an internal short, open circuit, or degraded performance that affects the reference voltage signal.

2. Damaged or corroded wiring/connector

Chafed, broken, or corroded wires and loose connections in the sensor circuit can disrupt the reference voltage, especially near hot exhaust components.

3. Short to ground or voltage in the reference circuit

The reference wire may be shorted to ground or to another voltage source, causing the voltage to be pulled out of the expected range.

4. Exhaust leak near the sensor

A leak upstream of the sensor can introduce fresh air, causing the sensor to read lean and potentially affecting the reference voltage performance.

5. Contaminated or fouled O2 sensor

Oil, coolant, or excessive carbon deposits on the sensor tip can insulate it or cause slow response, leading to reference voltage errors.

6. Faulty PCM (rare)

The PCM provides the reference voltage; an internal failure is possible but should only be considered after all other causes are ruled out.

How it's diagnosed

  1. Use a scan tool to verify the P2248 code, check for other related codes, and record freeze frame data.
  2. Visually inspect the bank 2 sensor 1 wiring and connector for damage, corrosion, or loose connections; repair as needed.
  3. With the key on and engine off, measure the reference voltage at the sensor connector using a multimeter; compare to manufacturer specifications (typically around 2.5V).
  4. Monitor the O2 sensor signal with a scan tool or oscilloscope while the engine is running; look for slow response, stuck voltage, or out-of-range readings.
  5. Check for exhaust leaks upstream of the sensor that could cause false readings.
  6. If no other faults are found, perform a voltage drop test on the reference circuit between the PCM and sensor, and consider PCM testing only as a last resort.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)
Related codesP2240 — O2 Sensor Positive Current Control CirP2241 — O2 Sensor Positive Current Control CirP2242 — O2 Sensor Positive Current Control CirP2243 — O2 Sensor Reference Voltage CircuitopeP2244 — O2 Sensor Reference Voltage PerformancP2245 — O2 Sensor Reference Voltage Circuit Lo

Frequently asked

What does the P2248 code mean?

It means the engine computer has detected a performance issue with the reference voltage circuit of the oxygen sensor on bank 2, sensor 1. This sensor helps control the air-fuel mixture, and the fault may be due to the sensor itself, wiring, or rarely the computer.

Can I drive with a P2248 code?

You can drive short distances, but the vehicle may run poorly, use more fuel, and could eventually damage the catalytic converter. It's best to diagnose and repair the issue promptly.

Is the PCM likely to be the cause of P2248?

No, the PCM is rarely the cause. Many drivers are incorrectly told to replace the PCM, but the problem is almost always a faulty O2 sensor, wiring issue, or exhaust leak. Always rule out simpler causes first.

How do I fix a P2248 code?

Start by inspecting the sensor and its wiring. Replace the O2 sensor if it is contaminated or damaged. Repair any wiring faults or exhaust leaks. Only after thorough testing should the PCM be considered as a possible cause.