Emissions

P01F3 — O2 Sensor Circuit High Voltage (Bank 1, Sensor 4)

Severity: medium Safe to drive

What P01F3 means

The engine control unit watches oxygen sensor signals to judge exhaust content, fuel mixture and catalyst performance. P01F3 usually means the circuit for the Bank 1, Sensor 4 oxygen sensor is reading too high a voltage. Note that this code is listed as reserved in the generic SAE list, so its exact meaning can vary by manufacturer. Confirm the definition for your specific vehicle before replacing parts.

Symptoms

  • Check Engine light on
  • Reduced fuel economy
  • Rough or unstable idle
  • Occasional minor misfire
  • Higher emissions readings

Possible causes

  1. Failed, aged or contaminated oxygen sensor
  2. Open or shorted wiring in the sensor harness
  3. Corroded or loose connector
  4. Sensor heater circuit fault
  5. Exhaust leak or air leak near the sensor
  6. Fuel mixture problem upstream of the sensor
  7. Control unit software glitch (rare)

How to diagnose

  1. Read all codes and freeze frame data and confirm what P01F3 means for your vehicle
  2. Find out from the service info where Sensor 4 sits on your car
  3. Inspect the sensor harness and connector for chafing, corrosion, oil and heat damage
  4. Watch live sensor voltage and heater status on a scan tool
  5. Check short and long term fuel trims for a rich or lean condition
  6. Inspect the exhaust for leaks near the sensor
  7. Test power, ground and signal wires with a multimeter per the wiring diagram
  8. Clear the code and see if it returns

Common fixes

  • Replace the Bank 1 Sensor 4 oxygen sensor
  • Repair the wiring or connector
  • Fix any exhaust or air leak
  • Correct the cause of the wrong mixture
  • Update the control unit software if the manufacturer offers it

Questions and answers

What does P01F3 mean?

It usually points to high voltage in the Bank 1, Sensor 4 oxygen sensor circuit. The generic SAE list shows it as reserved, so confirm the exact definition for your make and model.

Can I drive with P01F3?

Generally yes for a short time. Fuel use and emissions may rise, so it's best not to put off diagnosis.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.