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Discussion Starter · #1 ·
Hi,

just wondering what happens when the check engine light turns on a T5 or R. Some say that the ECU then lowers the boost to protect the engine. Is this always the case??? Or is it error code dependant what the ECU does (if anything)?
 

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Originally posted by Cyphos:
Cyphos
don't have an answer but your question is quite timely....my 2000R blk/blk with ipd dual and ECU upgrade just had the Check Engine light light up in the last couple of days....I think tha tmy girlfriend failed to tighten the gas cap at the pump. My understanding is that the check engine light usually signals a fault with emissions readings (often as a result of improper cap tightening) but sdoes not effect performance or drivability. That said before I read your post I really thought that my FAST R had gone a little soft but hoped I was losing my mind instead! I feared that the Check Engine had wiped out my ipd upgrade.
Let me know what you find out. I'm due for service and will have it all checked out soon.
Jim
 

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Your right about the emissions thing. That's one of the only reasons, plus the gas cap thing, that makes the light come on. Kind of annoying that you can't turn it off without the tool.

I had increased the boost on my T5 slightly well before this light came on and haven't noticed a difference since its been lit. It came on while driving hard in traffic in Boston, think my cats may have overheated. But no change in performance noted. Keep us posted if you find out if it's true (about the lowered boost).

Tony P

98 V70 T5
 

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As I write this my wife is calling our two local independant shops as the check engine light just went on in her '98 V70AWD. Just want them to plug in and diagnose it. Already tightened the gas cap and restarted(rebooted?) the car and nothing changed. It came on while the car was sitting and idling in a parking lot for 5 minutes on a hot day.
 

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quote:

Originally posted by TravelingIncognito:
Yep, that was it. The gas cap was loose and the check engine light came on while we were sitting still and the engine was idling. Our local indy shop pulled the codes and that is what it said. They shut the light off as well. Glad it was nothing more.
 

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Discussion Starter · #7 ·
Okay,

after asking around and getting many different opinions, these were the most popular ones:

The light is most often related to emissions problems. Malfunctiong cat, etc... When this is the case, only thing that happens is that the check engine light turns on. Nothing else. (This goes also with the gas cap thingy already discussed here in the previous posts.)

And when the car goes into limp home mode, boost and rev limiter are dropped drastically by using another ECU program. You can't use more than a few gears in your auto tranny. And the check engine light will light up to tell you there's a problem with your car. This is the case whenever a fault is detected e.g. in the tranny.

--edit-- Please correct me if I'm wrong!! --edit--

My check engine light has been on for ages... The error code is always the same, a malfunctiong catalytic converter. I've already had my cat replaced with a new Ferrita racing cat. And while my warning light is on, the boost is still at normal level. Has anyone had similar problems?


BTW, had my tranny replaced. Hope the new one lasts until I get my next car...
 
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