new codes... :(

smatt1079 · Post by **smatt1079** » 08 Mar 2008, 10:37

I put a new starter in my 95 850 turbo this morning.

Good news, the car starts now

Bad news, the check engine light came on with codes p0120 and p0123. The car also idles high in neutral, but fine in park and in gear. However, if I rev the engine while in park, it has a hard time coming back down, which is something I've never heard of!

When I reset the light they come back on immediately.

What have I screwed up now?

Post by **MadeInJapan** » 08 Mar 2008, 10:47

Both are codes for a faulty signal from your accelerator pedal position sensor.
If you open your hood and look at the brake fluid reservoir, just to the left and slightly lower than the reservoir, you'll see a cylinder looking protrusion from the round, large, black brake booster cylinder that has a connector on it. This is your Pedal Position Sensor. Take the connector loose and clean it good with contact cleaner. See if this does it. If not, you might be in for a new one of these. I you want to check voltage, without depressing the brake pedal, the circuit should read exactly 1.0 Volts with engine running and car at idle. Open circuit or much higher voltage may indicate a need for replacement. Also if you haven't touched your brakes since changing your starter, you might try depressing the brake pedal several times, then resetting your codes again to see if this restores things (always have your radio code ready when you do this).

Good luck and if you need further assistance on the pedal position sensor, let us know. There are two types made for your car so it's important to know which one to get if replacement becomes necessary.

smatt1079 · Post by **smatt1079** » 08 Mar 2008, 11:16

hrmmm, ok, cleaned the connections with electric contact cleaner, and its a hair better.

The codes still come back immediately, but when I put it into neutral it revs high and then backs down, slowly.

But, if I give it gas in drive or neutral it revvs high and i have to shut it off to get it to stop revving high (or shift it, which probably isnt good for the trans...)

So, am I in for a switch? Is that otherwise known as a throttle position switch?

speaking of the transmission, that flashing up arrow is going. Its done this before but usually only after we havent driven it in a while. Since its been two or three weeks since the starter kicked the bucket and I only just changed it today I'd say that qualifies as a while...

smatt1079 · Post by **smatt1079** » 08 Mar 2008, 11:19

oh, and also, I drove the car for a good mile since changing the starter. The brakes had been frozen since it was sitting so long. The brake pedal seems kind of hard now. does one have anything to do with the other? What does the brake booster have to do with the switch? (just curious)

Post by **MadeInJapan** » 08 Mar 2008, 11:20

I edited my post so re-read it. The throttle position switch is different. The arrows sounds like a PnP switch. Do a search, but you're getting codes for the switch I mention. You might try reading the voltage on the sensor with a multimeter.

smatt1079 · Post by **smatt1079** » 08 Mar 2008, 11:29

hrmmm, i dont have a multimeter. I dont really know how to use one either. Is this a normal thing to happen?

How does the switch come out? I cant tell.

It's a longshot but I'm going to clean all the other connections I had undone to do the starter and see if anything changes.

Post by **MadeInJapan** » 08 Mar 2008, 11:39

Here's how the switch comes out (and back in) if you need to go this far:
(Before you do any of this though, with the car off, push the brake pedal several times to release all the vacuum. Otherwise, it will suck the o-ring into the booster.)

Post by **MadeInJapan** » 08 Mar 2008, 12:09

I just thought of something and I hope I'm not having you bark up the wrong tree. When I look up Pedal Position Sensor in VADIS, the above is what I get, but it just crossed my mind that this may be the BRAKE pedal position sensor and the codes you got were for the ACCELERATOR pedal position sensor. Not sure if they're both the same or not. Couldn't find anything in VADIS for the accelerator sensor. I'm deeply sorry if this isn't your issue.

On later models there's actually a sensor at the gas pedal. Look under your car to see if it has one. If not, it could be as simple as the wire going to the throttle not engaging/disengaging smoothly. Three is a part right before the throttle that the cable winds on and off of...check it to make sure your throttle wire isn't hanging up. I've sprayed the whole contraption with silicone spray before to make it move easier.

Just a thought, but after I posted all of the above, I got concerned.

smatt1079 · Post by **smatt1079** » 08 Mar 2008, 12:30

well, I was taking your word for it, and I've cleaned that thing a dozen times. But, when I google the codes I find TPS failures listed.

But, I dont think this is the (only) idle problem. So, while I was cleaning the connections that I had undone when I changed the starter I noticed that the silver part under the plastic housing near the throttle body had some crappy looking connections. I cleaned them up an plugged it back in, but no change.

So, I unplugged it. It idled higher than normal but it didnt do the thing where it idled too high and then wouldnt stop.

So, I googled the part number and found out its the idle regulator valve. Now, since I'm having a problem with idle, somehow this makes sense.

So, as luck would have it, I have a spare idle regulator valve. Yes, I know this is strange, but still lucky.

So I cleaned this one off and plugged it in. Its idling the same as when I had the first one unplugged (seems high, but its not revving itself up higher and higher).

Of course, the CEL is still on with the same two original codes.

The up arrow is still flashing, and its not shifting right...

I think i'm moving in the right direction anyway.

smatt1079 · Post by **smatt1079** » 08 Mar 2008, 12:46

cleaned the TPS connection (which I never unplugged) and all is right with the world. The flashing arrow even went away.