Tim,
Check this out from Jay:
never2muchboost
Supporting Vendor (Gold)
p0129 is barometric pressure out of range .it gets set under the following condition:
if the map sensor signal is greater than 4.9v for 300 milliseconds it will set this code.
fucked up thing about this code is map runs off a 5 volt reference and isnt directly wired to the pcm.believe it or not any 5 volt sensor could cause this problem.
i went throught this with psichicks car.for those of you with a one time code reset the pcm and maybe it wont come back.
MAMADOR; i dont know how handy you are but if you check the wiring to the map sensor you will probably find the 5 volt reference pulled to a low due to a shorted sensor somewhere on the k7 5 volt supply circuit.
backprobe the 5v wire if you dont show 5 volts then start unplugging the sensors on that circuit until you see your 5v come back at the map.
one sensor shorting out will pull them all to a ground and give you whats happening.in amy's case it was the speed sensor shorting out and causing it.
sensors on that ckt are;
speed sensor
cam sensor
crank sensor
map sensor
tps sensor
Here is the post:
Engine code P0129?
