Hey I've been getting this code the last few weeks and it is confusing me. It says "secondary upstream manifold air pressure sensor low" the code will go away and then come back for no apparent reason. I've read some threads about it and they mentioned checking the bpv for possible broken spring. I reached in and the spring seems fine. It is stuff and springs back the way I would expect it to.

I'm at a loss could it possibly be a bad tmap sensor? Looking for any help or advice. Also this is the only code that is popping up.

 

Check the vacuum hoses that connect to the BPV. Facing the car from the front, the hose is on the top of the engine, at the left side intercooler bell. There is a tee in it, check those as well.

 

Also check your IC boots.

 

Do you possibly have a picture of that vacuum hose? Another side note there is a loss of power between 2500 and 3200 rpm. I'm sure this related based on previous threads.

 

Let me see what I can find. Make sure you check the IC boots.

 

Should I go ahead as completely remove the IC to check the boots?

 

You can or just look real close at them. Make sure they are tight. IF you take the IC off you will see the other vacuum line to check. Im trying to find you a good picture to help you.

 

I do appreciate the help very much. I will take a close look at things tomorrow.

 

Did you have any luck?

 

I will check it this afternoon. I have church and then lunch with the family. I will keep you updated. I'm thinking that if it is the boots I might run over to the alta headquarters and get their silicone boots.

 

So I pulled the intercooler and inspected the boots. My apologies for no pictures but everything looked good to go. There was a bit of an oily build up inside the boots and a little in the intercooler. I also inspected all the lines to look for anything disconnected or loose and did not find anything.

On one side I guess finding nothing out of the ordinary is good but on the other still unsure what could be causing the code. I have not gone through a full drive cycle yet so maybe just moving things around a bit was enough.

Any other ideas what could cause the P1237 code?

 

Try resetting the code and see if it comes back. It could be the sensor itself is bad.

 

That would be the one on the intake manifold correct? Front of engine?

 

Got in the car and the code went away on its own. I'm still skeptical since it was doing this off and on anyways. I will update if/when it comes back.

 

Fingers are crossed for you.

 

P 01237 is referring to the upstream map sensor. It is located to the left of the air filter box. Between the head and air filter box.. Replace the map sensor and all should be well.

Jason

 

Just as I suspected it appears the code has come back. I will check later to ensure it is the same one but I'm fairly positive it is. Next step I suppose is the sensors. Can we confirm which one it is? Is it the on on the front or the one beside the intake?

 

The code refers solely to the upstream map sensor which is the one next to the intake. The Tmap sensor is the downstream sensor located at the front of the motor after the supercharger.

 

Thanks I will give that a shot next looks like.


Today the light went off again... While it was off I was in 2nd around 2500 rpm and I blipped the gas and quickly brought the rpms up to 3400 or so. The light came on right after I did that. This is not the first time I was able to replicate this. I am just wanting to lay out everything I've experienced in case some one comes across this same issue later.

 

So here is a half update. I was able to have the light off for four days in a row before it coming back on. I should be replacing the sensor next week sometime. I will update again then if that solves my issue.

 

Did this work? I am having the exact same issue.

 

So I never did end up changing out the sensor. I did unplug it and inspect the wires for corrosion but there was none. I think that removing the intercooler and checking the connection point to the sensor scared the code away because I have not seen it since the last I had updated this. Sorry I can't be if more help.

 

update: I didn't replace the sensor either. I did however remove the intercooler and checked all the vacuum lines. The vacuum line connected to the bypass valve was 95% falling off. So loose that when I barely touched it, it did come off. I re-seated all the vacuum lines, zip-tied them, and the check engine lite is gone.

I think the JCW vacuum line T for the intake creates extra pressure forcing the vacuum lines off their connections.

 

Bumping this. I'm having the exact same problem as the OP. AWheatle, can you provide a photo of the vacuum line you're referring to? When I installed the Detroit Tuned BPV I didn't see any vac lines that went to it. Surprised me honestly since I figured the system needed vac to control the valve.

Also, does anyone know what the car should be reading for vac while at idle? I'm usually at around 18-19 in/HG.