Car with unfixable TPS code

Tiny
CLEARANCEMAN
  • MEMBER
  • 2000 SUBARU LEGACY
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 144,000 MILES
I don't know what to do, neither the dealer or a local shop that just fixes Subarus has been able to fix this car in more than 2 years.
2000 legacy wagon L I bought it new in 1999.
A few years ago, it started with TPS (throttle position sensor codes). The dealer replaced every sensor, the fuel filter, etc. Proclaiming it fixed each time. I couldn't afford to keep doing this, so I went to a local shop. They are much cheaper but still can't figure out what is wrong. Here is what it does: It is not the TPS or the computer. I'm 100% sure. I have replaced both with no effect. TPS has been adjusted for voltage over and over too, no effect.

When you first start the car, it often shows low voltage TPS code and most of the time the ATF yellow light flashes. You can't drive it with the ATF light flashing (it slams gears) so I have to restart. Sometimes more than 10 times to get the ATF light to stop flashing. It rarely shows this code at start up if the temperature is below freezing (32 degrees). Occasionally, but not very often. It does it most of the time if the temperature is above freezing.

It sometimes throws the ATF flashing light in stop and go traffic, always as a result of TPS code. It does it most at start up, less in stop and go traffic. It also surges at random at idle and in traffic. The only way I have found to get rid of the flashing yellow ATF code is to restart the car.

On the highway, it sometimes stumbles and surges when the throttle is off (down a hill) but rarely throws the flashing yellow ATF code.

So I have noticed, the ATF code (and of course TPS code) is related to the amount of throttle. And at start up, it is also related to temperature. When under load (giving the car throttle), it doesn't occur.

Local shop noticed some TPS voltage fluctuation and asked if the TPS was replaced. This is with a brand new (bought last week) TPS in place. So there is low TPS voltage at 0 throttle and minimal throttle, but not at higher throttle levels.

Voltage at idle off the alternator is excellent, that was a thought that the local shop had. But it is 13 to 14 volts even at idle with accessories running.

Last week it started showing the factory security system on (red light blinking in the instrument panel) any time the engine is off. Doors closed or open, unlocked. It's always blinking. It doesn't set the alarm off though unless the doors are locked like normal. It just indicates it is armed. The security light goes off when the car is started. I have no idea if this is related to the TPS code. I care much less about the security system problem then fixing the TPS problem.
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Monday, March 2nd, 2009 AT 7:59 AM

30 Replies

Tiny
MERLIN2021
  • EXPERT
TECHNICAL SERVICE BULLETIN Reference Number(s): 16-65-99R, Date of Issue: April 03, 2000 Related Ref Number(s):

DESCRIPTION In the event you encounter a customer complaint of the A/T temperature light flashing and this code is found in the TCM, perform the following: First, eliminate all wiring and connector concerns by performing the tests as outlined in the appropriate Service Manual for this code. Repair as necessary. After you have checked and confirmed these items, and you still did not find any problems, we recommend you replace the following part(s). Use the chart below to locate and order the correct part number(s) for your application
.


http://www.2carpros.com/forum/automotive_pictures/62217_suba_1.jpg



That part # is 31711AE10B I'm not sure what it is but it mifgt be the TCM itself...Stop in at Subaru, they can tell you if it's been done on yours yet, Transmission control module?
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Monday, March 2nd, 2009 AT 3:06 PM
Tiny
CLEARANCEMAN
  • MEMBER
Could the code be low voltage TPS because that is the only one that ever shows up. No TCM codes despite the flashing ATF light at times.
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Monday, March 2nd, 2009 AT 6:40 PM
Tiny
MERLIN2021
  • EXPERT
I think it's worth the effort to find out if the has been done or not, strange things happen with eleictrical and computer faults.
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Wednesday, March 4th, 2009 AT 6:37 AM
Tiny
CLEARANCEMAN
  • MEMBER
The TCM has definitely not been done. Can I use one from a 2001 or 2002? Different part number. I'm having trouble locating a used one for 2000 on ebay and a new one is $400.
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Thursday, March 5th, 2009 AT 9:29 PM
Tiny
(HELP)
  • MEMBER
I'm wondering why "every sensor" would have been replaced>Does the (butterfly) shaft in the throttle body have a lot of play? I seem to remember seeing these replaced - I suggest you give a different dealer or Subaru specialty shop your next oil change business and run the story by them - Also I noticed the factory Shop Manual on CD is very inexpensive on ebay - there's a LOT of info in them but the translation from Japanese makes it hard to dechipher sometimes.
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Thursday, March 5th, 2009 AT 9:59 PM
Tiny
MERLIN2021
  • EXPERT
Check the part number on the chart, it's the only one for your car that will solve the problem.
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Friday, March 6th, 2009 AT 7:01 AM
Tiny
CLEARANCEMAN
  • MEMBER
Ok, I'll check the butterfly valve. The local dealer is clueless, they just replace parts and call it fixed, they have no idea what is wrong. It's had 2 O2 sensors, a MAP sensor, 2 knock sensors, three TPS sensors. I replaced the computer. Hasn't had the TCM or the butterfly shaft. Can't figure out why temperature makes a difference either, above freezing way more problems than below freezing.
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Friday, March 6th, 2009 AT 9:25 AM
Tiny
POGODOG
  • MEMBER
Wow, finally I have come across someone who is having the same problem as I am

Let me do a quick run down here:

I also own a 2000 Legacy L 2.5 Wagon with 80k

My car has the same symptoms as yours does

I have replaced the TPS twice

Replaced the ECM (engine control module)

Just recently (about a week ago) I replaced the transmission control module (still nothing)

Car will be driving fine then all of a sudden the AT Temp light will start flashing and transmission will slam into gear with lots of throttle hesitation. As you stated above sometimes pulling over and shutting engine off will turn AT Temp light off. I'm at the end of my rope with mechanics unable to properly diagnose this problem (they rely way too heavily on scanning machines) I continue to get the same trouble code that suggests that the throttle position sensor needs to be replaced (again)

Does anyone have any sound advice on what is causing this problem? Any suggestions on something related that could be causing it? I'm at wits end and really don't know what to do
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Saturday, March 21st, 2009 AT 4:54 PM
Tiny
MERLIN2021
  • EXPERT
It sounds like a manufacturing defect, time to call
N.T.H.S.A. At 1-888-327-4236, file a complaint, when they get a few of them, they force recalls.I agree about the techs and scan tools, but until the genius at the top who designed the crap figures it out, it's all they have!
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Sunday, March 22nd, 2009 AT 10:26 AM
Tiny
KARENCAREN
  • MEMBER
My mechanic friend thank you all. He is looking for this info to fix the car that a client gave him. I'll let you know guys if he fix it.
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Wednesday, May 20th, 2009 AT 12:41 AM
Tiny
MORIYA
  • MEMBER
This was good to read. I also own a 2000 Subaru Outback. I have been experiencing the same issue since I bought the car used from a Subaru shop in West Virginia.

I had to replace the TPS sensor twice in the 1st 3 months. I then drove across country and had to replace the TPS again! Then, the car started messing up again and the mechanics just can't figure it out. They replaced the computer as well as the battery. At one point I was told that I needed to take out my floor mat because it was too "heavy". Seriously?

Agreed. I only have troubles with the TPS Sensor when it's hot outside. Not sure what's up. However, after 3 years of issues, I'm sick of dealing with it and paying for it. I'm calling N.T.H.S.A. At 1-888-327-4236.

Let's pray for a recall!
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Friday, August 14th, 2009 AT 11:58 AM
Tiny
MERLIN2021
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Check the shaft in the throttle body for movement, should be none. Open the trhottle part way, then push up and down on the plate, should not move (sideplay).
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Tuesday, August 18th, 2009 AT 12:48 PM
Tiny
CLEARANCEMAN
  • MEMBER
I hadn't checked this in awhile. My car now has 171,000 miles on it. It is pretty bad, I have to turn it on and off 6-7 times each day, I have tried every suggestion given to me and it hasn't helped at all. I think I will dump it on carmax when it needs its next timing belt at 195,000. Anyone ever find a solution?
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Friday, October 16th, 2009 AT 7:20 PM
Tiny
MERLIN2021
  • EXPERT
Right now only God seems to know!
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Friday, October 16th, 2009 AT 7:27 PM
Tiny
CLEARANCEMAN
  • MEMBER
I did call the NHTSA and I submitted my complaint. The biggest problem is the car is unsafe and cannot be made safe. It should be taken off the road.
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Thursday, October 29th, 2009 AT 7:25 AM
Tiny
CLEARANCEMAN
  • MEMBER
I hope more people report their problem to the NHTSA because they won't open an investigation until they get enough complaints. Carmax offered me $500 for my car so I'm still driving it. It has 178000, I guess it's mine for now, I can't get anything for it and it works well in the snow when I'm not restarting it 5-6 times per day. I've gotten pretty good at restarting it. I drop it in neutral and restart wherever I am. Only place I can't do that is stop and go traffic up hill. Then I have to stop and restart.
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Wednesday, December 23rd, 2009 AT 7:51 AM
Tiny
MERLIN2021
  • EXPERT
I wonder how many years this goes on for? A friend of mine bought a Subaru wagon, 2005 new, and before it got off the Dealer's lot, it needed a new TPS.
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Thursday, December 24th, 2009 AT 6:59 AM
Tiny
GWLUND
  • MEMBER
I also have a 2000 Subaru Legacy with a TPS code and hesitating around 2000 RPM. It is intermittent and happens mostly when the engine is warm. My local shop has a Subaru knowledge base that says that the electrical wiring and/or connector is suspect. If you look at the 180 deg bend that the wire makes out of the TPS you can see why there might be an intermittent contact that causes the voltage reading to fluctuate.

Anyone tried to replace the wiring/connector? Looks like the dealer wants you to pay $300 to replace the entire wiring harness.
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Friday, February 26th, 2010 AT 10:24 PM
Tiny
GWLUND
  • MEMBER
Also, I've played with strain reliving the connector with zip ties and tape and can get the problem to go away for a few weeks but it ususally comes back. Might also be a bad wire that gets hot when you drive and causes the resistance to go up. Having an extra voltage drop in the wire can cause the ECM to see a low voltage. The best way to check is to wire in a shunt wire at the TPS and monitor the voltage in parallel to the ECM. If the ECM see a low voltage and the parallel meter does not then the problem is in the connector/wire.
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Friday, February 26th, 2010 AT 10:28 PM
Tiny
MERLIN2021
  • EXPERT
If there is a lot of tension at the plug, it could also be stressing the TPS itself? Test when hot!
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Saturday, February 27th, 2010 AT 8:44 AM

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