The MAP sensor is a critical engine management system component. When it fails, engine performance will suffer.
In this article, I'll answer some of the most commonly asked questions about the manifold absolute pressure (MAP) sensor.
Contents of this tutorial:
APPLIES TO: This article applies to the following vehicles:
- 1.7L Honda Civic DX: 2001, 2002, 2003, 2004, 2005.
- 1.7L Honda Civic EX: 2001, 2002, 2003, 2004, 2005.
- 1.7L Honda Civic GX: 2001, 2002, 2003, 2004, 2005.
- 1.7L Honda Civic HX: 2001, 2002, 2003, 2004, 2005.
- 1.7L Honda Civic LX: 2001, 2002, 2003, 2004, 2005.
What Does A MAP Sensor Do?
The manifold absolute pressure sensor measures the vacuum pressure inside the intake manifold.
It then sends this manifold vacuum report to your Honda Civic's fuel injection computer.
The fuel injection computer then uses this manifold vacuum information to calculate engine load and inject the correct amount of fuel (into the cylinders).
Here are the specifics of how the MAP sensor functions:
- When the MAP sensor senses a high vacuum pressure, it produces a low voltage value.
- When the MAP sensor senses a low vacuum pressure, it produces a higher voltage output.
What Happens When A MAP Sensor Goes Bad?
The fuel injection computer monitors the manifold absolute pressure sensor the entire time the engine is running, so when it fails, it will set a MAP sensor diagnostic trouble code.
Since the manifold absolute pressure sensor is a critical component of the engine management system, engine performance will suffer when it fails.
The following section will go into more detail.
What Problems Can A MAP Sensor Cause?
The most obvious symptom you'll see when the MAP sensor fails is the check engine light illuminated by a MAP sensor diagnostic trouble code.
You'll see one of the following diagnostic trouble codes registered in the computer's memory:
- P0107: MAP Sensor Circuit Low Voltage.
- P0108: MAP Sensor Circuit High Voltage.
- P1128: MAP Sensor Signal Lower Than Expected.
- P1129: MAP Sensor Signal Higher Than Expected.
You're also going to see one or more of the following symptoms:
- Bad gas mileage.
- Lack of power.
- Black smoke coming out of the tailpipe.
- Engine suffers a very rough idle.
- The engine may start and immediately stall.
- The engine has to be cranked longer than usual for it to start (this is called extended cranking).
- A heavier than normal exhaust smell when the engine is running.
- Won't pass the emissions test.
How Can You Tell If A MAP Sensor Is Bad?
The best way to know if the manifold absolute pressure sensor is good or bad is to test it.
See the next section to find out more.
Can I Test The MAP Sensor?
You can quickly test your 1.7L Honda Civic's MAP sensor's performance with a multimeter and a vacuum pump (you'll need the vacuum pump to apply vacuum to the MAP sensor).
The MAP sensor test procedure is as follows:
- Check for MAP sensor trouble codes with a code reader or scan tool.
- Make sure that the MAP sensor is receiving 5 Volts DC.
- Make sure that the MAP sensor is receiving Ground.
- Make sure that the sensor's MAP voltage signal decreases/increases as vacuum is applied/released to it.
- NOTE: This test step requires that the MAP sensor remain connected to its electrical connector (although it is not connected to the manifold's vacuum supply).
If the MAP sensor's voltage signal does not decrease/increase as you apply/release vacuum to the sensor, you can conclude that it's bad and needs replacement.
The following tutorial will help you to test the MAP sensor using a vacuum pump and a multimeter:
Can I Drive My Vehicle With A Bad MAP Sensor?
Your Honda Civic's fuel injection computer will activate its 'limp' mode when the manifold absolute pressure (MAP) sensor fails.
'Limp' mode limits your Honda Civic's engine performance to a considerable degree to ensure the MAP sensor fault doesn't cause any engine damage.
Depending on the severity of the symptoms that the 'limp' mode or the faulty MAP sensor is causing, your Honda Civic will not be safe to drive.
Where To Buy The MAP Sensor And Save
You can find the MAP sensor in any auto parts store. If you're wanting/needing to save a few bucks, then buying the MAP sensor online is the route to take.
The following links will help you comparison shop for the MAP sensor:
More 1.7L Honda Civic Tutorials
You can find a complete list of 1.7L Honda Civic tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- How To Test The Crank Sensor (2001-2005 1.7L Honda Civic).
- Maintenance Required Light Reset (2001-05 1.7L Honda Civic).
- How To Do A Cylinder Balance Test (2001-2005 1.7L Honda).
- How To Test The TP Sensor (2001-2005 Honda 1.7L).
If this info saved the day, buy me a beer!