Fuel and air

P00EF — Intake Air Temperature Sensor 3 Circuit Low, Bank 2

Severity: low Safe to drive

What P00EF means

The engine control module monitors the voltage in the circuit of intake air temperature sensor 3 on bank 2. The sensor is a thermistor: warmer air lowers its resistance and signal voltage. P00EF sets when the voltage falls below the expected range, so the module reads impossibly hot air. The usual culprits are the sensor itself, a signal wire shorted to ground, or a bad connector.

Symptoms

  • Check Engine light on
  • Rough idle
  • Reduced fuel economy
  • Sluggish throttle response
  • Hard starting or power loss (not always)

Possible causes

  1. Failed intake air temperature sensor
  2. Signal wire shorted to ground from damaged insulation
  3. Corroded, dirty or wet connector terminals
  4. Open or shorted wiring near hot or moving parts
  5. Rarely, a faulty engine control module

How to diagnose

  1. Read the codes and freeze frame data, clear the code, and see if it returns.
  2. Use the vehicle's wiring diagram to locate IAT sensor 3 on bank 2.
  3. Inspect the connector and harness for chafing, melting, moisture and corrosion.
  4. With a scan tool, compare the sensor reading to ambient temperature on a cold engine; they should be close.
  5. Unplug the sensor: if the reading jumps to the open-circuit value (usually very high), the wiring to the module is likely fine and the sensor is suspect.
  6. Check for about 5 V reference and a good ground at the connector.
  7. Test the signal wire for a short to ground back to the module.
  8. Measure sensor resistance and compare to the manufacturer's spec at a known temperature.

Common fixes

  • Replace the intake air temperature sensor
  • Repair wiring insulation or replace the damaged harness section
  • Clean or replace the connector and terminals
  • Diagnose, reprogram or replace the ECM only after ruling out everything else

Questions and answers

What does P00EF mean?

It means the module sees a low signal in the intake air temperature sensor 3 circuit on bank 2. The cause is most often the sensor or a signal wire shorted to ground.

Can I drive with P00EF?

Usually yes, for short trips. The engine may run less smoothly and use more fuel, so don't put off the check.

How do I fix P00EF?

Start by inspecting the connector and wiring, then check the sensor's live reading with a scan tool. If the wiring is good, replace the sensor.

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.