P0113 is an OBDII trouble code that occurs when the Pontiac Sunfire’s engine management computer detects that there is an issue with the Intake Air Temperature (IAT) Sensor, specifically that there is a High Input Problem with it.
P0113: IAT Sensor → High Input Problem
The IAT sensor is responsible for measuring the air temperature and density to achieve the optimal air/fuel mixture for any condition.
P0113 is specifically thrown when the Sunfire’s computer sees a voltage signal of 4.91 volts for over half a second at the Intake Air Temp Sensor. If there are irregularities in the voltage, it will not throw P0113, it’s only for excess voltage.
Pontiac Sunfire P0113 Symptoms
There can be symptoms associated with P0113. Depending on the time of year, IAT sensor issues can be a real problem. When it is cold outside, it may be more difficult for your Sunfire’s engine to start. This is due to a lean condition that’s more noticeable when the air temperature is lower.
Here are the most common symptoms of P0113/IAT issues:
- Service Engine Soon– Often, the only noticeable symptom of P0113 is going to be the service engine soon light.
- Hard Starts– the engine may have difficulty starting due to the IAT issue creating a leaner air fuel mixture. As stated above, this problem will only be magnified when it is cold outside in the engine needs more of a choke to start.
- Lean Condition– As stated above, the engine will run lean with P0113. It is not a good idea to drive around for a long time with an engine is running lean. We recommend getting it in to be repaired as soon as possible. Once the engine is warmed up though, it should not leave you stranded.
- Decreased Fuel Economy– With the engine running lean, it’s not going to produce the optimal power for good fuel economy.
P0113 Diagnosis: Pontiac Sunfire
Here’s a really helpful YouTube video that has a lot of good information to help diagnose P0113.
When most folks see this trouble code, they will replace the IAT sensor right away. It is often a mistake to replace the sensor immediately, often it will be a wiring issue.
It’s a good idea to inspect the wiring around the sensor, and make sure that there are no obvious signs of damage, or that it is even plugged in. After that, use a multimeter to make sure that it is getting the proper voltage. A good scan tool can tell you a lot about what exactly is going on with your engine and causing the P0113.
If you have looked around the harness and there does not seem to be any discernible problem, it will most likely be the IAT sensor that needs replaced.
Here are some of the most common causes of P0113, presented (somewhat) in order from most likely to least likely:
- IAT is bad, and needs replaced.
- IAT is good, but oil has contaminated it (on the tip).
- Wiring harness has been damaged/shorted: How to Diagnose a Short in a Car (youtube) Find a short in a car (article).
- Backfiring has occurred in the intake manifold. This can fry/contaminate the sensor.
- PCM failure.
While P0113 is not going to leave you stranded on the side of the road, it is important to not ignore it. If you allow your Pontiac Sunfire to run lean for too long of a period of time, it’ll develop other problems with the engine. Good luck fixing your vehicle. If there is anything that you would like to add to improve this article, please leave a comment below.