5 Symptoms of a Bad IAT Sensor
The sensor is essential to computer-controlled engines like the B. IAT. It measures the temperature of the incoming air. A faulty intake air temperature sensor can affect your vehicle’s air-fuel ratio, leading to drivability and performance issues.
But what exactly are the symptoms of a bad IAT sensor? Can you keep driving? And how much will it cost to replace the sensor? What is an IAT sensor? As the name suggests, the Intake Air Temperature Sensor monitors the temperature of the air being introduced into the intake tract of your engine.
Simply put, your engine’s IAT sensor acts like a thermometer with respect to the air that is ultimately delivered to each cylinder for combustion. However, instead of displaying a mercury reading, the IAT sensor provides feedback to the ECM/PCM in the form of a voltage.
The motor’s control software then interprets this voltage reading and converts it into a logical temperature feedback. This feedback is used as a key value to determine the air-fuel ratio required for efficient combustion. This point relies on the fact that cold air has a much higher oxygen density than warm air, and is therefore more likely to ignite.
Symptoms of a Bad IAT Sensor
Failure of your vehicle’s intake air temperature sensor is often accompanied by a number of secondary symptoms, some of which are more noticeable than others. It is important to be aware of these individual symptoms when attempting to troubleshoot the problem at hand.
1) Check Engine Light Illuminated
In most cases, a faulty IAT sensor will cause your vehicle’s check engine light to illuminate. This occurs when your vehicle’s ECM or PCM has stored one or more trouble codes resulting from such a failure.
2) Rough or Erratic Idling
A faulty IAT sensor will often cause your vehicle’s engine to idle abnormally or stall noticeably when stopped. This is because the engine cannot accurately determine the air-fuel ratio required for efficient combustion.
3) Difficulty Starting
Another obvious sign of a faulty IAT sensor is difficulty starting. Your vehicle’s ECM/PCM will not be able to determine the proper fuel trim level, compromising your engine’s ability to start smoothly.
4) Misfires
When your intake air temperature sensor starts to fail, random engine misfires will often occur. Again, this is caused by a lack of accurate temperature readings as your vehicle’s ECM/PCM tries to determine the correct amount of fuel to deliver.
5) Poor fuel economy
If your engine’s IAT sensor is on the verge of failing, you may also feel a bit of pain at the gas pump. Increased fuel consumption is often due to over-fueling caused by out-of-spec intake air temperatures. Where is the sensor located?
Engine intake air temperature sensors are most commonly located in the intake runner that connects the engine’s air filter housing and throttle body.
In some cases, a vehicle’s IAT sensor may be located elsewhere, such as in the intake manifold or air filter housing itself, but this placement is far from standard, but has become more common over the past decade. What causes the sensor to fail?The most common cause of intake air temperature sensor failure is contaminant buildup on the sensor’s probe.
These contaminants often appear in the form of traces of oil, but any kind of deposit floating around in your engine’s intake tract can cause similar problems. If this type of contamination is severe, it will “short” your engine’s IAT sensor.
Intake air temperature sensors can also fail simply due to age and normal wear and tear. This is especially common in older vehicles or vehicles with high mileage. Unlike dirt fouling, when an intake air temperature sensor fails in this way, cleaning alone is rarely enough to fix it.
How long does an IAT sensor last?
This is primarily due to the sensitivity of the IAT sensor itself and its tendency to become contaminated by oil and other particles in the engine’s intake tract.
In most cases, you can expect your vehicle’s intake air temperature sensor to last an average of 5-10 years, although this lifespan can vary greatly from case to case.
However, this does not mean that your vehicle’s IAT sensor will definitely fail within this time frame, as it is not uncommon for this type of sensor to last significantly longer under ideal circumstances.