1985-1991 Buick Skylark Engine Intake Manifold Temperature Sensor Guide
This small, affordable sensor can be the hidden cause of rough idling, poor fuel economy, and hard starts on your Skylark.
- A faulty IAT sensor on your Skylark will most commonly cause a rough idle, poor gas mileage, and hesitation.
- This is an excellent DIY repair for beginners; the sensor is easy to access and replace with basic tools.
- For this part, a quality aftermarket brand like Standard Ignition offers a reliable and much more affordable alternative to scarce OEM parts.
- Before replacing, check if the sensor is just dirty, as cleaning it can sometimes restore its function.
Understanding the Intake Air Temperature Sensor on Your Skylark
On a 1985-1991 Buick Skylark, the Intake Air Temperature (IAT) sensor plays a key role in how your engine performs from day to day. This sensor tells your engine's computer how hot or cold the air is that's being pulled into the engine. The computer needs this information to create the perfect air-fuel mixture for combustion. Cold air is denser and has more oxygen, so the computer adds more fuel; hot air is less dense, so it adds less fuel. When this sensor fails, the computer gets bad information, leading to a host of noticeable engine problems.
Symptoms of a Failing IAT Sensor
A bad IAT sensor can mimic other fuel or ignition problems. Watch for these common signs:
- Check Engine Light: This is often the first sign. The computer will log a fault code related to the IAT sensor circuit.
- Poor Fuel Economy: If the sensor incorrectly tells the computer the air is cold, the engine will run rich (too much fuel), wasting gas.
- Rough Idle: An incorrect air-fuel mixture can make the engine idle unevenly or even stall.
- Hard Starting: Especially when the engine is cold, a bad sensor can make it difficult to start because the fuel mixture is wrong for the conditions.
- Engine Hesitation: During acceleration, the engine might feel sluggish or hesitate if the computer can't adjust the fuel mixture correctly.
- Failed Emissions Test: An improper air-fuel ratio leads to incomplete combustion, which will increase harmful emissions.
Choosing the Right Aftermarket Sensor
For a vehicle like the 1985-1991 Skylark, finding original equipment (OEM) parts can be difficult and expensive. The OEM part number for this sensor is GM 25036751. Luckily, the aftermarket offers reliable and affordable alternatives. The IAT sensor is a simple electronic component, and a quality aftermarket brand is a perfectly suitable replacement.
Standard Ignition (Standard Motor Products) is a well-established brand in the aftermarket industry, known for producing engine management parts since 1919. Their products are engineered to meet or exceed OEM specifications and are manufactured in TS 16949 certified facilities, ensuring quality and reliability. For this specific sensor, Standard Ignition is a trusted and cost-effective choice.
Pro Tip: Check for Contamination First
Sometimes, the sensor isn't broken but is simply covered in oil or carbon buildup. This contamination can insulate the sensor, preventing it from reading the air temperature correctly. Before buying a new part, it's worth removing the old sensor and inspecting it. If it's dirty, cleaning it with a dedicated mass air flow or electronic parts cleaner might solve your problem. Be gentle, as the sensor element can be delicate.
Estimated Replacement Costs
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket (Standard Ignition) | $18 - $31 |
| New OEM (GM/ACDelco) | $47 - $72 |
| Shop Labor | $50 - $100 |
Frequently Asked Questions
Where is the IAT sensor located on a 1985-1991 Buick Skylark?
The IAT sensor is typically located somewhere in the air intake path. It is often threaded directly into the intake manifold or located in the air cleaner housing or intake ducting, between the air filter and the throttle body. It is a small, two-wire sensor.
Is this the same as the Coolant Temperature Sensor?
No. The IAT sensor measures air temperature, while the Engine Coolant Temperature (ECT) sensor measures the temperature of the engine's coolant. Both are critical for engine management, but they perform different functions and are not interchangeable. A bad ECT sensor will cause different symptoms.
Can I replace this sensor myself?
Yes, this is a very DIY-friendly repair. The sensor is usually easy to access and simply unscrews from its mounting location. The process involves disconnecting the electrical connector, unscrewing the old sensor, screwing in the new one, and reconnecting the connector. It typically requires only basic hand tools and can be done in under 30 minutes.
What happens if I don't replace a bad IAT sensor?
While the car will likely still run, ignoring a bad IAT sensor will lead to persistently poor performance. You will experience reduced fuel economy, rough running, and potentially hard starting. Over the long term, running a consistently rich or lean fuel mixture can contribute to increased carbon buildup on internal engine components and potential damage to the catalytic converter.
Technical Specifications
OEM Part Numbers: 25036751
The IAT sensor is a two-terminal thermistor that is threaded into the intake manifold or air cleaner housing. Its resistance changes with air temperature, which allows the ECU to calculate air density. For example, one service manual notes a resistance of 177 ohms at 212°F.
We Have This Part in Stock
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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