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Can a rusted through exhaust cause a CEL? Topic is solved

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Clemens
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Can a rusted through exhaust cause a CEL?

Post by Clemens »

On my newly acquired 94 855 T5M I have a massive exhaust leak and a check engine light. THe blinky box didn´t throw out anything I could identify during a snowstorm when I bought it. Just wondering if a crack in the exhaust could cause the CEL? I think yes if is between Oxygen sensor 1 and 2 (downpipe, cat).

Also, the Turbo works really fine, not the boost gauge. Could a broken vacum hose to the gauge cause a CEL as well? Just thinking about this because the car is at my indie getting all the holes in the body welded up and I´m thinking about what to do to get it driveable.
Summer: 1996 855 R
Winter: 1994 855 T5M
Donor: 1995 854 10V

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rspi
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Post by rspi »

What is the code?
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Clemens
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Post by Clemens »

If only I could remember. It was cold and I was young and needed the money... You know how these stories end.

Seriously: I need to lool it up again as soon as I get it from the mechanic who does the safety inspection. Without the code it is just guessing. I was just wondering if this could theoretically be the cause.
Summer: 1996 855 R
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Post by wizechatmgr »

I would doubt it unless it was before or between one of the two oxygen sensors. Take that with a grain of salt as I'm a volvo newbie...
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Post by Ozark Lee »

Sure, either one or the combination of the two can cause a CEL. The boost gauge is fairly simple to trace, at least back to the firewall and often it the hose slipping off of the hard plastic pipe up near the radiator. The front oxygen sensor is the most sensitive and an exhaust leak ahead of that will jack up the fuel trim.

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Clemens
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Post by Clemens »

Thanks. That's what I wanted to know
Summer: 1996 855 R
Winter: 1994 855 T5M
Donor: 1995 854 10V

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misha
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Post by misha »

Clemens wrote:...Just wondering if a crack in the exhaust could cause the CEL? I think yes if is between Oxygen sensor 1 and 2 (downpipe, cat)...
You allready answered to your own question.
I would just add....there is one more point which is a flexible pipe between exhaust manifold and cat(manifold & front o2).
If the car have just front o2 sensor...every exhaust leak after it CAN'T trigger cel.
If there are 2 o2 sensors,every leak after rear o2 sensor CAN'T trigger cel.
That's it.
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