I have a persistent p2229 code (baro sensor high voltage) that I simply cannot get to go away. I'm out of ideas at this point.
I have a stack of MAP sensors, including the old one, a couple of Chinese ones I bought, and a brand new GM one. All of them output 4.69 or 4.7 volts at atmosphere. Apparently, anything over 4.5 will set a code. Both the barometric pressure sensor to ambient, and the supercharger inlet pressure sensor (same part number from what I can tell) output the exact same voltage at ambient pressure. Under vacuum, they both reduce in voltage output, as they should. Sensor reference input is 5.03 to 5.04 volts, and that's both for the supercharger and the ambient sensor.
I've searched the Cobalt forums, which was unhelpful. A couple of people had similar issues, but either never solved them, or never bothered to post back the solution. I suspect most of them simply replaced the sensor and that fixed it, but obviously that hasn't worked here.
In my VCM scanner, The barometric pressure is listed as 15.1 psi, And it seems to be constant even if I apply vacuum to the sensor. Unplugging the sensor drops it to 1.51 PSI, which is odd that it's a multiple of the original value, but at least it changes. The change makes me think the PCM is seeing the sensor, Even if the readings are suspect.
At this point, my next step is to replace the PCM. I have little faith that that will work though. Replacing the computer is something that mechanics do when they run out of other ideas, and in my experience it's never actually fixed the problem. In all my years working on cars, motorcycles, airplanes, and semi trucks, I've never actually seen a bad ECM. They seem to be pretty reliable.
Anyone have any ideas about a p2229 code?
I have a stack of MAP sensors, including the old one, a couple of Chinese ones I bought, and a brand new GM one. All of them output 4.69 or 4.7 volts at atmosphere. Apparently, anything over 4.5 will set a code. Both the barometric pressure sensor to ambient, and the supercharger inlet pressure sensor (same part number from what I can tell) output the exact same voltage at ambient pressure. Under vacuum, they both reduce in voltage output, as they should. Sensor reference input is 5.03 to 5.04 volts, and that's both for the supercharger and the ambient sensor.
I've searched the Cobalt forums, which was unhelpful. A couple of people had similar issues, but either never solved them, or never bothered to post back the solution. I suspect most of them simply replaced the sensor and that fixed it, but obviously that hasn't worked here.
In my VCM scanner, The barometric pressure is listed as 15.1 psi, And it seems to be constant even if I apply vacuum to the sensor. Unplugging the sensor drops it to 1.51 PSI, which is odd that it's a multiple of the original value, but at least it changes. The change makes me think the PCM is seeing the sensor, Even if the readings are suspect.
At this point, my next step is to replace the PCM. I have little faith that that will work though. Replacing the computer is something that mechanics do when they run out of other ideas, and in my experience it's never actually fixed the problem. In all my years working on cars, motorcycles, airplanes, and semi trucks, I've never actually seen a bad ECM. They seem to be pretty reliable.
Anyone have any ideas about a p2229 code?