anyway to clear check engine light?

96turbowagon · Post by **96turbowagon** » 12 Apr 2008, 18:11

Last week I replaced my radiator and coolant temperature sensor. Everything was fine for maybe 15 minutes but then my check engine light came on. I had the code scanned and it shows PO172, System too rich. What might cause this and how do I get rid of the light to see if it happens again? thanks

Post by **MadeInJapan** » 12 Apr 2008, 18:23

Did you reset the computer after the radiator/temp. sensor change by disconnecting the battery for 15-20 minutes and pushing the brake pedal? This will reset the adaptives and could be the only thing wrong (Car is used to the way things ran before your replacements). However, that code is typical if you have a vacuum hose leak (among other things) so if resetting the adaptives doesn't work, for the first step, check your hoses real good. There is a small hose elbow right below the thermostat housing that you might have snagged. It's hard to see but might be the cause. To check, with car idling spray some carb cleaner around where you suspect the break in the hose to be. If the car surges, then you know you've found it. Good luck!

96turbowagon · Post by **96turbowagon** » 12 Apr 2008, 19:42

I didnt try resetting the computer, I didnt know how until now. lol. When do you push the brake pedal, after the 20 minute wait and while cranking or ?
Im glad to hear that it may be something simple, nothing but big headaches from the car lately, hopefully it will be as simple as resetting the computer or a vacuum leak. Id also like to say to you MadeInJapan that youve helped me heaps in the past few months and that I really appreciate it. Thanks

Hot Pepper Thai · Post by **Hot Pepper Thai** » 12 Apr 2008, 20:13

I don't know if someone has the correct answer but I have a similar issue with my 98 t5. I've just recently drove my car over 200 miles in one day and during the journey, I've discover that the temp gauge was hovering @ 4 o'clock (little cool). In town @ normal driving condition its @ slightly @ 3.3ish. My problem now is that the temp gauge is @ 5 o'clock (ever cooler) the rad fan comes on. It stays on and I don't know what is happening all of the sudden? The car is running extremely cooler and the coolant fan will not stop running. I finally had to discount my rad fan to stop it or I would have a drained battery. I turn off the car and when restarting the service light appears with a P0116. I reset the code with my OBD-2 but it seem to reoccurs. Can someone please tell me why the fan will not shut down? I don't know if 96 turbo has the same problem but I'm all ears with the fan,temp,dead-battery-fan code issue. Many thanks to MIJ and Kevin6 for all of their prior tips!!

Post by **MadeInJapan** » 12 Apr 2008, 22:05

P0116 is the coolant temp. sensor code. I suspect it is bad and also the reason your fan is coming on. When the temp. sensor goes it confuses the fan relay and strange things start happening to the fan (sometimes always on, sometimes never on). Anyway, any deviation at all from 3:00, I've learned to go ahead and change this sensor out along with the thermostat...why not, the parts are cheap and it's easy to do.

Post by **MadeInJapan** » 12 Apr 2008, 22:07

96turbowagon wrote:When do you push the brake pedal, after the 20 minute wait and while cranking or ?

Really, anytime during the time your battery is disconnected and before you try to crank it. It might not even be necessary, but evidently it helps purge the system completely of any electrical current that might still be hanging out.

Hot Pepper Thai · Post by **Hot Pepper Thai** » 13 Apr 2008, 20:18

Thanks MIJ, will do, I think you've hit the target on fan issue because it strangely coming on @ lower temp. Never knew a coolant sensor could trigger these condition. Thanks MIJ!

Hot Pepper Thai · Post by **Hot Pepper Thai** » 13 Apr 2008, 20:38

I forgot to ask you about setting the computer. You mentioned about disconnecting the battery for 15-20 minutes and pressing the brakes. My question is can you be more specific on the order after reconnection the battery? Its like turbo96 had the similar question regarding the steps. Thanks again for your help. Thanks MIJ! 98 T5

Post by **MadeInJapan** » 13 Apr 2008, 21:04

That's all you have to do to reset the adaptives (computer). After you have the cable off of the battery for 15-20 minutes and after you press the brake pedal, just hook the cable back up to the battery and that's it. What you did should have reset everything and you'll be able to start new with the computer reading all the sensors and your driving methods as if it were reading them for the first time.

Volgrrr · Post by **Volgrrr** » 14 Apr 2008, 05:36

MadeInJapan wrote:
96turbowagon wrote:When do you push the brake pedal, after the 20 minute wait and while cranking or ?
Really, anytime during the time your battery is disconnected and before you try to crank it. It might not even be necessary, but evidently it helps purge the system completely of any electrical current that might still be hanging out.

The answer is quite simple.

Putting your foot on the brake allows any residual electricity stored in any of the on-board retentive devices to dissipate to zero through a resistive circuit i.e. the brake filament.

Doing this eliminates any sudden 'zap' and thereby protects the many delicate electronic components on the vehicle.