What should the MAP sensor reading be with a scan tool with key on and engine off?


Mine reads 28.6 , but from what I have researched it should be the same as the current atmospheric pressure(30.00) before the engine is started and if it is not pretty close then you should go ahead and replace it. No code is currently being thrown, but after a few years they say the diaphragm begins to constrict and can throw off readings. It has never been replaced in 15 years.


The above question comes on the back of a recently received P0430 code(catalytic converter below threshold) which was read at autozone. I replaced the old gas cap and PCV valve and the code came back on after 100 miles. I went ahead and purchased my own scanner with live data to help diagnose problem after contacting local Honda dealer. They said without a doubt that code indicated that the catalytic converter needed to be replaced. I next replaced the rear oxygen sensor and front oxygen sensor. The code has not returned after 1000 miles and car runs almost like new. I think the primary problem was the rear oxygen sensor because of the relative constant high voltage readings.


Anyway I noticed that the MAP reading may be off and was considering replacing it also. Can anyone verify what the key on engine off reading should be?


Thanks.

 

If ECM is not reporting a MAP sensor code (P1128 or P1129) you don't have a problem. Manual says it should show approximately 30 in hg. IMO you are at approximately 30.

good luck

 

Where'd you get 30.00 in.Hg as atmospheric pressure (it's suspiciously even)? Standard (textbook) value or from a local weather report? How high elevation are you at?

That 28.6 is like 3500 feet above sea level, not even close to Denver's elevation (not knowing where you're located). And certainly within what might be caused by some weather systems.

 

Reading is from TV weather station. Elevation is 1300 feet.


Springfield, MO

• Feels Like: 79° F 26° C
• Wind: 7 mph 11 kph at NNW
• Humidity: 60%
• Dew point: 64° F 18° C
• Barometer: 30.00 inches 1016 millibars and rising

 

Sorry, the even 30 just caught my suspicion...

The important part of the question is that I don't really know how close to 30 it really needs to be. Tex, does the manual say anything specific about that?

 

No tolerances were given only "approximately 30 in hg". Most electronic parts vary by 10-20 % depending on specification for accuracy.

good luck