Understanding P0111: Intake Air Temperature Circuit Range/Performance Problem

What is the P0111 Code?

The P0111 code is a diagnostic trouble code (DTC) that is typically triggered when the powertrain control module (PCM) perceives a problem with the intake air temperature (IAT) sensor. What exactly does this mean? Let’s delve deeper.

What Does Intake Air Temperature Circuit Mean?

The intake air temperature circuit is a component of the engine management system that monitors the temperature of the air entering the engine. It’s a vital part of the system, helping to adjust fuel injection and ignition timing for optimal performance and fuel economy.

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Causes of P0111 Code

The P0111 code can be triggered due to a few different reasons.

Faulty Intake Air Temperature Sensor

The most common cause is a faulty IAT sensor. If the sensor is not providing accurate readings, the PCM may trigger the P0111 code.

Wiring or Connector Issue

Another common cause is issues with the wiring or connectors that link the IAT sensor to the PCM. If these components are damaged or corroded, it could lead to the P0111 code.

Engine Control Module Problem

Though less common, problems with the PCM itself could also cause this code.

Symptoms of P0111 Code

P0111 code often comes with some noticeable symptoms.

Check Engine Light

The most apparent symptom is the Check Engine Light illuminating on your dashboard.

Poor Fuel Economy

You might also notice your vehicle isn’t as fuel-efficient as it once was.

Engine Misfire

In some cases, you might experience engine misfire or a rough idle.

How to Diagnose P0111 Code

Once you’ve noticed these symptoms, how do you go about diagnosing the issue?

Inspection of Intake Air Temperature Sensor

Start by visually inspecting the IAT sensor. Look for any signs of damage or wear.

Checking Wiring and Connectors

Next, check the wiring and connectors for any signs of damage or corrosion.

Testing the Engine Control Module

If everything else looks good, you might need to test the PCM.

How to Fix P0111 Code

Now that you’ve diagnosed the issue, how do you go about fixing it?

Replacing Intake Air Temperature Sensor

If the sensor is faulty, it will need to be replaced.

Repairing Wiring and Connectors

If the issue is with the wiring or connectors, these components will need to be repaired or replaced.

Replacing Engine Control Module

In rare cases, if the PCM is the problem, it may need to be replaced.

Prevention of P0111 Code

The best way to prevent the P0111 code is regular maintenance. This includes routinely checking the condition of the IAT sensor and associated wiring and connectors.


Understanding the P0111 code is essential for keeping your vehicle running smoothly and efficiently. With knowledge of what causes this code, the symptoms to look out for, and how to diagnose and fix the issue, you’re well-equipped to handle this problem should it arise. Regular vehicle maintenance is key to preventing this and other codes.

Frequently Asked Questions (FAQs)

  1. What does the P0111 code mean? The P0111 code is a diagnostic trouble code indicating a problem with the intake air temperature sensor circuit.
  2. What causes the P0111 code? This code can be caused by a faulty intake air temperature sensor, issues with the wiring or connectors, or problems with the engine control module.
  3. What are the symptoms of the P0111 code? Symptoms may include a lit Check Engine Light, poor fuel economy, and engine misfire or rough idle.
  4. How do I fix the P0111 code? Fixing the P0111 code may involve replacing the intake air temperature sensor, repairing or replacing damaged wiring or connectors, or in rare cases, replacing the engine control module.