Owning a Car: What Newbies Need to Know

DIY: Problem With Your Manifold Absolute Pressure Sensor?

by Avery Ellis

Your manifold absolute pressure sensor reads the pressure within the manifold and the ambient barometric pressure. This delicate balance of pressure allows your vehicle's computer to balance things, like your fuel-to-air mixture, and also keep your fuel injectors working as they should. But this sensor can fail, and you should be able to recognize the signs. And if necessary, you can change the sensor yourself.

Symptoms of a Bad Manifold Absolute Pressure Sensor

Look for the following signs:

  • Your check engine light may be on. You can have your auto care specialist help confirm your suspicions.
  • Rough engine performance when accelerating or slowing down because your computer is receiving an imbalanced pressure reading.
  • Bad emissions from your exhaust pipe because your car may be running lean or rich.
  • Your engine might surge because your computer is making your car run with a bad air-to-fuel mixture.
  • Spark plugs with a black residue leftover from improper combustion.

Talk to your auto care specialist if you notice the aforementioned symptoms so that he or she can confirm your suspicions. Some of these symptoms could also be due to a fuel pressure regulator or a bad idle air control valve. After confirming, you can follow the steps below if you choose to fix the problem yourself.

Replace Your Own Manifold Pressure Sensor

You'll need the following:

  • Socket and wrench set.
  • Owner's manual or repair manual.
  • Safety glasses and gloves.
  • New manifold absolute pressure sensor for your specific car.


  1. Park your car on safe and leveled ground.
  2. Make sure the car has been off long enough to cool down the engine so that you can work comfortably.
  3. Put your safety glasses and gloves on.
  4. Unhook the negative cable from your car battery for your protection.
  5. Find the manifold absolute pressure sensor. It is usually on the right side of your engine, behind the injectors. You can use your owner's manual or repair manual to find the sensor.
  6. The sensor is usually connected to an electrical plug. Remove this plug by pressing on the tab and unplugging it carefully.
  7. Remove the bolts holding the sensor in place using your socket and wrench set.
  8. Bolt down your new sensor, and connect the electrical plug to your new sensor. Be sure to dust off any debris from the cable before reconnecting it. Make sure the tab clicks and that the cable is connected well.
  9. Reconnect the negative cable to your car battery.

That is how simple it is to change the manifold absolute pressure sensor in your vehicle. Do not hesitate to talk to your auto care specialist if you are not comfortable performing the job on your own. To learn more, visit Blue Valley Garage.