Understanding P0112: Intake Air Temperature Circuit Low Input

The P0112 error code is a common issue in vehicles, but what exactly does it mean? How does it affect your vehicle, and more importantly, how do you fix it? Let’s dive into the details.

What is P0112?

P0112 is an OBD-II trouble code that stands for ‘Intake Air Temperature Circuit Low Input.’ This code is triggered when the Powertrain Control Module (PCM) detects a lower than expected input voltage from the intake air temperature (IAT) sensor.

The Role of the Intake Air Temperature Sensor

The IAT sensor plays a crucial role in how your car operates. It measures the temperature of the air entering your engine and sends this information to the PCM. Based on this data, the PCM adjusts the air-fuel mixture, ensuring optimal engine performance. Therefore, any issue with the IAT sensor can lead to engine problems.

Causes of P0112 Code

Several issues can cause a P0112 code. These include a faulty IAT sensor, wiring issues like short circuits or open circuits in the IAT sensor circuit, or even a faulty PCM, though this is relatively rare.

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Symptoms of P0112

So, what symptoms might you notice if your vehicle has a P0112 code?

Engine Performance Issues

The most noticeable symptom will likely be engine performance issues. Your car may consume more fuel than usual, lack power, or have difficulty starting, especially in cold conditions.

Warning Lights

Another symptom of a P0112 code is the illumination of the check engine light on your dashboard. In some cases, the light may flash, indicating a more serious issue.

How to Diagnose and Fix P0112

Fixing a P0112 code involves a few steps, starting from basic preliminary checks to more advanced diagnostics and sensor replacement.

Preliminary Checks

Start by checking the IAT sensor itself. Ensure it’s not physically damaged and is correctly connected. Also, examine the wires and connectors for signs of wear or damage.

Advanced Diagnostics

If the preliminary checks don’t reveal any issues, advanced diagnostics may be necessary. This process can involve using an OBD-II scanner to read the fault code and a multimeter to check the IAT sensor’s resistance and voltage. Always refer to your vehicle’s service manual for specific procedures.

Replacing the Intake Air Temperature Sensor

If the IAT sensor is faulty, it will need to be replaced. Ensure you replace it with a suitable model for your specific vehicle.

Preventing P0112

Preventing P0112 involves regular maintenance and promptly responding to warning signs.

Regular Maintenance

Regular vehicle maintenance, including routine inspections of the IAT sensor and its wiring, can help prevent a P0112 code. Pay particular attention to the condition of the wiring and connectors, as these are common sources of problems.

Responding to Warning Signs

If you notice any of the symptoms of a P0112 code, such as engine performance issues or warning lights, it’s essential to take action promptly. Early diagnosis and repair can prevent more serious and costly damage.


Understanding the P0112 code, its causes, symptoms, and how to fix it, can save you both time and money. Regular maintenance and early response to warning signs are key to preventing this error. However, if the issue persists, don’t hesitate to seek professional help.


Q1: Can I drive my car with a P0112 code? A: While your car may still be drivable with a P0112 code, it is not recommended. The code indicates a problem with the intake air temperature sensor, which can affect engine performance and fuel efficiency.

Q2: How much does it cost to replace an intake air temperature sensor? A: The cost to replace an IAT sensor can vary widely depending on your vehicle’s make and model. Generally, the parts cost between $20 to $50, but labor costs can add significantly to the total.

Q3: Can a P0112 code cause a car to fail an emissions test? A: Yes, a P0112 code could potentially cause a vehicle to fail an emissions test. The IAT sensor impacts the engine’s air-fuel mixture, which can affect emission levels.

Q4: Can a faulty IAT sensor affect fuel economy? A: Absolutely. The IAT sensor provides data to adjust the air-fuel mixture for optimal combustion. If it’s faulty, your engine may receive an improper mixture, leading to increased fuel consumption.

Q5: How often should I inspect the IAT sensor and its wiring? A: Regular inspections during routine vehicle maintenance are recommended. If you notice any performance issues or warning lights, check the IAT sensor and wiring as soon as possible.