Bad Coolant Temp sensor hurts starting?
 

Just got my 94 LSI back after 7 weeks in the body shop for a repaint (just repaint, dings only insheetmetal). It came out great.

However CE light is now on and morning starts are near impossible. It turns over but does not catch. If it does then it stops quickly. It takes 5-6 tries and pedal coaxing. Once started it stays rough for minute or so before reving up. Once reved up it starts easily for the whole day even with 4-8 hrs in between. Next morning same thing.

I had my local mechanic that I trust implicity and he could not get any codes to read out.

I brought it over to the local dealer (I know uh oh!) this morning and he claims he got a code for a bad coolant temp sensor that he claims could affect startup.

Anybody experience this or know if dealer is correct. Part is $54 and 2 hrs labor at $90/hr. UGH! :mad:

I was thinking maybe a bad fuel pressure regulator that lost pressure over night, 10-12 hrs sitting. Anyone know if a there should be code readout for this.

I tried running it for nearly a week to see if I could blow out any bodyshop dust or lingering paint fumes from sensors but no luck. even reset CE by disconnecting battery but it came right back.

Any comments.

I'm not sure how much it cost me...but I know that the bad coolant temp sensor does cause trouble at start up. Not sure if that helps much but i tried:rolleyes:

Petesvx2, thanks for the reply. It does help. At least the dealer may be on the right track. As long as it get fixed without adding anything else. iI can accept the $250 after everything else I've put into her.

It does add up to being the WTS as you have been told.

The temperature sensor comprises a thermistor and the resistance should reduce when the temperature rises i.e. from a high resistance when the engine is cold. (It has a negative temperature coefficient.)

When cold the resistance should measure 2,000 -3000 ohms and at operating temperature around 300 ohms. From this you will see that a short circuit would result in the engine receiving a signal that the engine is up to temperature when trying to start.

You should first check wiring and connections, then test the WTS if you have an ohm meter, or simply replace it.

It does not sound like a fuel pressure regulator to me (it takes fuel pump a split second to restore the pressure). It does not sound like a leaking injector either (4-8 hours should be long enough for any leaks to have the effect).

Temperature sensor sounds like a reasonable suspect.

Two hours of labor for the coolant sensor seems a bit excessive.
Unless they include time to diagnose the problem in this quote.
The temperature sensors are accessible from the top of engine compartment - you should be able to replace them yourself and do it in about 15 minutes.

However I doubt the sensor would go bad just from sitting for 7 weeks. Most likely it is an electrical connector - take an ohmmeter and check the sensors. SVX utilizes 2 temperature sensors - one for ECU, the other one for the temp gauge. This is a bit unfortunate - you cannot diagnose bad sensor by just looking a the temp gauge.

Take the connectors off the sensors, measure the resistance - should not be short, should not be open, should be single KOhms depending on the temperature.
Decent ohmmeter is around $20 at radioshack.
Put the connectors back and hope you problem is fixed :-)

$250 to replace the coolant temp sensor is nothing short of criminal. Yes, if the sensor is bad you can have problems starting the car - I had the same problem on both my Legacy and SVX. Your symptoms sound similar.

I paid about $25 for the sensor at my dealership in Michigan. The Legacy's took maybe 15 minutes to install and the SVX's took all of five.

I'm not kidding. The SVX's was very easy to get to and took no time at all to replace. An hour or labor - especially at $90 per hour - is absolutely criminal.

As for whether or not the sensor would be damaged by the car sitting, I would say no. But the sensor is a common failure on both the Legacy and SVX (I would assume the Impreza, as well, but can't say because I've never owned one).

I recommend that you buy the sensor from one of our supporting vendors online and have your trusted mechanic friend install it.

I had a similar problem with starting and I got the sensor. It is very easy to replace--less than 10 minutes. Instantly solved the starting problem and that was two years ago.
Good luck.

Thanks to all for the response. I am printing the threads and will stop at the dealer to check out how they came to their price. Probably hiding behind diagnostics. I know the owner well enough to complain if Service does not satisfy me. I have bought 5 Subarus from them (2 were Svxs) so I expect some loyalty despite never having much service done there.

I'll let all know how I make out.

Again, thanks for info and support.

I hope it works out for you, man. 2 hours of labor to replace something that takes no more than 5 minutes is insane. They're just trying to rip you off. Tell them to show you the book. They'll know what you mean. They're supposed to go by a book that tells them how long to estimate certain repairs for. If the book says 2 hours, go somewhere else because that's nothing short of robbery.

I can see one hour, including a road test and clearing the code from memory, but even that's stretching it. Replace the sensor and the problem goes away - if they got the code from the computer then they know exactly what to do. This is a common failure - very common.

Got the car back this morning and it started from a cold overnight with no issue at all. It was the WTS.

Got no where on the hours as they claimed tough time getting readouts. 1 hr then 1hr to replace. WTS was $25. I then corrected their computer records and got my 10% discount on parts and labor as new car buyer there (5 previous Subarus) and the total came to $225.

But it's working fine and we are now on the road again!

They confirmed rear engine seal was leaking which I knew about. I am going to try Lucas Stop leak. Car has been sitting a lot over last two months and I hope Lucas fixes this problem. Dealer wants $1225 to replace rear main seal.

Thanks again to all for the input and sympathy.:D

They probably claimed that it was tough to get readouts because getting the codes from a pre-OBD-II car is a tiny bit more complicated than getting them from an ODB-II one.

Still, I think they ripped you off. But I'm glad you have your car running and are happy.