caliEG2dr

okay so my Engine Check light has been on for the past 2 days, i went to go get it checked today and the outcome was Code 5 -- MAP: manifold absolute pressure sensor. Is there any possible things I can do at home to fix the problem before bringing it to a shop, which will charge $50-$90 for just the diagnoses, and then a repair job?

Honda Civic EJ1 fully bone stock.

thumper64

You can replace it, they're pretty cheap. Make sure the connections are good on the old one. It seems like more often than not, corrosion is to blame.

caliEG2dr

My car does have corrosion because it originated from the East Coast, where winter + salted roads = rust. If i were to replace the MAP, it doesnt solve the problem though, would it? Because it can be from a unblanced mixture of air a fuel.

caliEG2dr

"If i were to replace the MAP" --- replacing the MAP sensor, the small black sensor

delsolproblems

The MAP sensor reads the intake manifold vacuum. While a problem with it can cause a bad air/fuel ratio, a bad A/F ratio wouldn't necessarily cause a MAP sensor code. Even if the code is from something else like a broken wire, you can save the receipt and return the sensor if it doesn't fix the problem.

caliEG2dr

So, i should try replacing the MAP sensor first?

thumper64

Technically, there is no such thing as vacuum. The air all around us is at ~14.7 PSI (atmospheric pressure). "Perfect vacuum" is 0 PSI. So vacuum is just less than atmospheric pressure.

Any MAP sensor from pretty much any Civic, Accord, Integra, Prelude, etc will work. If I recall correctly, they're all the same.

delsolproblems

The simplest solution is just buy a new one and hook it up real quick in the parts store parking lot. If you want to test it, you first warm the car up to normal operating temperature, set the brake and leave it running. Set a meter to 20v and wedge the black probe in the battery negative terminal. Pierce the sensor signal wire (red/grn) with the red probe. The voltage reading should correspond to the amount of vacuum being generated inside the intake manifold. On MT versions of your motor, somewhere between .4 and .7 volts would be a good reading at normal idle. Higher voltage at standard idle speed usually means a vacuum leak. Next, shut off the motor and turn the key to on. Pierce the sensor's power wire (yel/red). There should be about 5v. Remove the probes and set the meter to resistance. Pierce the sensor's ground wire (grn/wht) with the red probe and wedge the black probe in the battery negative. There should be no resistance. Any resistance is a problem with the ground circuit but miniscule resistances can often be ignored. Remember to turn off the meter, take your key back and you're done testing the MAP sensor.

caliEG2dr

So, i didnt replace the MAP sensore, but instead i went ahead and bought a throttle body cleaner spray and sprayed the whole thing down. It didn't fix the problem. My next 2 options are replacing/test a new MAP sensore or testing if it holds a vacuum, which is best? or shall i try testing the voltage.

delsolproblems

Replace it. Switching one vacuum line and one harness connector will be the simplest next step and a MAP sensor code is more often than not a bad sensor.