Car died on the highway this morning :( P1507 CEL

[warrior]

Cruising to work and the check engine light comes on.. no biggie, I didn't notice any change in my engines performance and traffic was moving around 60km/h. Traffic started to slow down some more and I clutched in and the car died! I let off the clutch to start it again and car starts.. now I get cautious.

I turn off my music and accelerate in 3rd gear and the car has noooooo pick up! I manage to make it all the way to work which is about 15km away barely chugging along. Park in the parking lot, the car is idling about 500rpm and sounds like it's going to die.. quickly pop the hood and pull off one of the wires to see if it's a wire problem and the bastard thing shocks me cause I pulled it off too fast.. haha oops.. that was exciting.

Anyhow, with the car off, I pull off all the wires from the coil pack and put them back on.. start the car and car runs normal again.. took it for a boot around the block and it's fine.. check engine light is still on. It was a wet morning so I'm guessing cylinder misfire? Also one of my wires were a used one from back in the Spring because when I was doing my HG change, the boot ripped apart so the mechanic gave me a used one that was lying around.. I'm guessing this is my culprit.. right?

[Huffer]

You have a lot of variables.
First thing is to determine what the CEL is, and go from there.

[Reason]

Hit up Autozone after work and have them read your code.

[warrior]

Hit up Autozone after work and have them read your code.

Wish we had an Autozone around here.. I'm in Canada and any place charges minimum $90 just to have a code read.. fucking ridiculous!

[Reason]

Ouch, no parts place will read it for you?

[Huffer]

Time to buy a Scan Gauge II... $90 is about 2/3rds the price of one.

[Reason]

Time to buy a Scan Gauge II... $90 is about 2/3rds the price of one.

$155 shipped by Paranoid fabrications on RS25. I plan on getting one real soon.

[warrior]

I started the car after work (it's been sitting in the parking lot since the morning) and no check engine light.. car runs fine! Drive all the way to my buddies garage who scans it for me and the only code that comes up is P1507 Idle Control System Malfunction (Fail Safe)... :S

Car runs fine though.. I still think it was a cylinder misfire and because of that, it caused this code and since the sun dried up all the moisture in the air, the misfire no longer exists.. so I purchased a new set of NGK wires and we'll see what happens when it rains again.

My subaru mechanic is coming to look at it this evening.. eek!

[warrior]

Update:

Scan Gauge II refuses to read anything on my car except voltage. :roll:

I thought maybe it was the unit so tried GadgetGuy's and same thing; his unit works fine in his car.

I took my car to Subaru and I have a P1507 and P0303 code that both come and go. This is really messed up.. yesterday evening when I took my car to Subaru, the CEL decides to turn off, they scan the codes in memory and those were it.. cars been running just great since then. On the way to work this morning, check engine light turns on, cars running normal.. but when I clutch in to shift gears, rpms drop so fast and car stalls.

I turn the car off, turn it back on again.. everything resumes to normal! CEL is still on of course, but I bet on the way home, it will go off again.. bah.. I changed my wires to NGK's, I sprayed water mist all over the wires thinking they might be arcing somewhere but nothing.

I plan to change my plugs to the NGK Copper ones hopefully.. and lastly, I think I need a new IACV :(

Any other suggestions?

[Huffer]

Update:

Scan Gauge II refuses to read anything on my car except voltage. :roll:

I thought maybe it was the unit so tried GadgetGuy's and same thing; his unit works fine in his car.


You have to set the Scan Gauge settings - sometimes it doesn't read depending on which OBD protocol it's set to.
It's in the user manual at the back for Subaru's..

[warrior]

Follow up:

Even though P1507 refers to IACV, it doesn't mean it's broke. I bought Reason's IACV and swapped em.. same problem. I read on NASIOC that this is sometimes caused by the neutral switch in the tranny. This part is $30 from the dealer and pretty easy to replace. Replaced that and my problem went away. Apparently the neutral switch does more than just tell the ECU the transmission is in neutral.

I had a 2nd code come up, that was a knock sensor.. replaced that as well and now my car runs normal again. If you ever get a P1507, start with the neutral switch if your symptoms are similar to mine!

[evan55]

Bumping an old thread..

I'm having the same CEL P1507. I was going to try to clean out the IACV, and put a new gasket in, but the screws are on so tight, and they are really soft metal...

Should I just replace the neautral switch? Where is it?