My check engine light on my 1999 V70 XC lately will come on when starting the car and then not appear again. It appears to be very irregular. I might not see it for a few days and then it will come on. Then it will go off. Weird, could this be something beginning to fail? Gas cap is on firm.......

Check all of the Vacuum Elbows. The primary suspect (if it's one of these) is found under the t-stat housing coming off the intake manifold and connecting to a hose that runs down under the engine. It can be hard to see (use a flashilght) and even harder to get to. I just replaced mine. Often, the heat and grime will cause the rubber to go soft and either collapse or open a hole.

As was mentioned, be sure to get the codes read. Go to Autozone, they'll do it for free. It will be the generic code, not the "Volvo code," but it's a good place to start.

Sam

Have the trouble codes read and go from there. Without the codes (and sometimes even with the codes) it is impossible to tell why CE light is going on. That light will go on for any number (a large number) of reasons. Once you have the codes you can look them up in a pocket manual or ask here if you don't have the pocket manual. The pocket manual costs about $20 from Volvo and is well worth it. It has all the trouble codes, VIN decoding and loads of other information that is very useful. It comes in a form of a small book that fits into your pocket or glove box. Get it, it's worht it.

Good luck.
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Vladimir. '98 S70 base, 5-speed manual (his), '91 240 sedan automatic (hers).

On a 99 it could be the Evap purge valve. It's a known original defective
part. I have an intermittent CEL and hope the new valve fixes it.
All engine operation seems just fine.

The replacement part number for my c70 is 9470775. Yours may be the same.
It costs under $20. It is the adapter/coupler looking gizmo that has two
hoses and one electrical connections next to your driver side high beam.
It seems to be plug & play.

My valve is coming tomorrow. Will report results.

rd
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99 c70 hptm #421