Guide to the Engine Intake Air Temperature Sensor for 1994-1999 GMC P3500
Keep your workhorse P3500 running smoothly by addressing a faulty intake air temperature sensor.
- A bad IAT sensor commonly causes poor fuel economy, rough idle, and a Check Engine Light with codes P0112 or P0113.
- Replacement is extremely easy for a DIYer, requiring no special tools and taking less than 15 minutes.
- For this part, a premium aftermarket brand like Standard Ignition offers reliable, OEM-level performance for less money.
- Ignoring the issue can lead to failed emissions tests and potentially long-term engine issues from running on the wrong fuel mixture.
Understanding the IAT Sensor in Your P3500
The Intake Air Temperature (IAT) sensor on the 1994-1999 GMC P3500 is a simple thermistor that plays a big role in engine management. It tells the engine computer how hot or cold the intake air is, which allows the computer to make constant adjustments to the fuel mixture and ignition timing. When this sensor fails, it can send incorrect information, leading to a range of engine performance problems. Fortunately, it is an inexpensive and easy part to replace.
Symptoms of a Failing IAT Sensor
A bad IAT sensor will usually let you know something is wrong. The most obvious sign is a Check Engine Light on your dashboard. Other common symptoms include:
- Poor fuel economy
- Rough or uneven idling
- Hesitation or poor acceleration
- Difficulty starting the engine
- Black smoke from the exhaust
- Failing an emissions test 🎬 Watch a breakdown of common bad IAT sensor symptoms.
Diagnostic Codes (DTCs)
If your Check Engine Light is on, a code scanner will likely show one of two codes related to this sensor. Code P0112 means the sensor circuit voltage is too low, while code P0113 means the voltage is too high. Both codes point to a problem with the sensor or its wiring.
Choosing the Right Aftermarket Sensor
For a vehicle from this era, you don't need to hunt down an expensive original equipment (OEM) part. Quality aftermarket brands offer reliable performance at a much lower cost. When shopping for a replacement, consider these tiers:
- Premium Aftermarket (e.g., Standard Ignition): Brands like Standard Motor Products (SMP) are well-respected in the industry and have a reputation for producing high-quality parts that meet or exceed OEM specifications. They perform extensive testing to ensure reliability and proper function. Choosing a brand like Standard Ignition is a safe bet for a long-lasting and accurate repair.
- Budget-Friendly (e.g., True Tech): True Tech is often positioned as a more economical option. While the name is associated with several well-regarded independent repair shops, the quality of parts sold under this brand name can be more variable than premium brands. For a simple sensor like the IAT, a budget part may work fine, but a premium brand offers more peace of mind regarding accuracy and durability.
Pro Tip: Location and Installation
On GM trucks from the mid-90s, the IAT sensor is typically located in the plastic air intake tube between the air filter box and the engine. It is usually a small plastic sensor held in by a grommet or screwed into the intake. Replacement is very simple: unplug the electrical connector, pull or unscrew the old sensor, and install the new one. No special tools are required.
🎬 See how to replace the IAT sensor on GM trucks.Frequently Asked Questions (FAQ)
Where is the IAT sensor located on the 1994-1999 GMC P3500?
The IAT sensor is almost always located in the air intake ducting, after the air filter and before the throttle body. On some GM engines, it may be screwed directly into the intake manifold. It will have a two-wire electrical connector attached to it.
Can I just clean the old sensor?
Sometimes, the sensor probe can get covered in oil or dirt, which affects its readings. You can try cleaning it with a dedicated mass airflow sensor cleaner. However, the sensor can also fail internally due to age, in which case cleaning will not help and replacement is necessary.
🎬 Learn more about the causes of IAT sensor failure.Do I need to reset the computer after replacing the sensor?
After replacing the sensor, the Check Engine Light should turn off on its own after a few drive cycles. You can also clear the codes immediately with an OBD-II scanner or by disconnecting the battery for about 15 minutes, which will reset the engine computer.
Are there any recalls for the IAT sensor on this truck?
A search of the National Highway Traffic Safety Administration (NHTSA) database did not show any recalls or widespread technical service bulletins (TSBs) specifically for the Intake Air Temperature sensor on the 1994-1999 GMC P3500.
Helpful Videos
Technical Specifications
OEM Part Numbers: 96253552 96279856
Connector Shape: Rectangular, Terminal Quantity: 2, Mounting Type: Screw-in or Push-in
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
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