ETC flashes, code po129 barometric pressure

[Jerry9]

2004 2500 hemi 110,000 trouble free miles until yesterday. At least it had the consideration to quit in a parking lot. ETC flashes, she cranks, starts, RPMs go wild then she shuts down. Towed home, consulted the internet, used cheap scanner to get code po129. Weird thing is clear the codes she starts and idles fine then shut her down and restart rpms go wild. I take the throttle body off to clean (youtube video), reinstall, turn key hold gas pedal down 20 seconds release slow, she starts and runs fine. I drive her around the yard, park it, shut it down then start it back up, rpms go wild and po129 code is read. Another youtube video has the guy replacing the cranksensor which fixes the problem. His symptoms were he measured 5 volts on a few sensors even with the key off. He traced it back to the cranksensor which was replaced and the problem was fixed. I don't mind too much throwing parts at her but I mind the down time. Also how would I really know if the problem is fixed with a new part which could mask the problem? Help please.

 

[FabricGATOR]

The MIL and codes do not diagnosis the engine faults, they are just clues. It is up to you, the technician to interpret the clues and diagnosis the fault.

I hope this helps you. Please hit the [ LIKE ] button…

Please return and tell how this information worked for you, what you find, and how you eventually fix your vehicle (even if it is that you brought it to a mechanic / dealership for repair)
It is your feedback and final repair report that will make these forums useful to others in the future.
Many times I search and find the same exact fault that I am having, someone suggests how to fix it, the patron follows the suggestion and then never returns to say YEA! or NAY...


The forum thread just goes dead because the person fixed their fault and has not a care to offer the answer anymore. Please don't be that guy.

Cheers!

 

[FabricGATOR]

I would be happy to help, but I am not familiar with that fault.
I have only owned my Hemi 5.7 for a week.

 

[chri5k]

The code is pointing to the MAP sensor. Check the wiring harness and the pins/socket in the connector going to the sensor. The outer wires are power and ground. The center wire is the signal. If you have a volt meter you can check for +5v and ground on those wires. If those check out, it may be the sensor.

 

[Jerry9]

Thanks for the replies. I installed a new electronic throttle body, crank, cam, MAP and air charge sensor. Did the throttle body calibration. Truck started right up and is now fine. Yes it was probably only one thing wrong but I need to be able to trust the truck and it was only a few dollars more. Got the parts from Amazon. Guess I got lucky that I got parts from them that fit and worked. Now to worry about the drive train seals that show signs of leaking.

 

[GTyankee]

powertrain control module (PCM) has detected a low barometric pressure reading from the barometric pressure sensor (BPS) or the manifold absolute pressure sensor (MAP).

Read more at: https://www.obd-codes.com/p0129
Copyright OBD-Codes.com
Is the best trouble shooters guide, in my opinion

possible causes:

Possible causes for this code include:
Corroded connector face at the MAF/BPS sensor
Insufficient engine vacuum due to engine wear, an ignition misfire or clogged catalytic converter
Faulty BPS Open or shorted wiring for the MAP sensor and/or the BPS Insufficient system ground at the MAF/BPS
Defective PCM or PCM programming error