My '94 940T Service Engine light always stays on for 2 to 4 minutes after I start the car. After that time is goes out.
The car has 189K (miles) on it and the engine seems to run fine.
What is this light telling me?
Do I need new O2 sensor, or AMM?
Or should I just disregard it it keep on trucking.
Thanks in advance for your input.
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EJO now a 1994 940T 190K; ex '63 123S; ex '75 245; and ex '81 242GT

I must be getting old as I forgot about the reset light, which I have done in the past B-4.
B-4 driving home from work last night I took a paperclip pushed the button (and also again did not loose the grommet) and of course all is okay now.
Thank you all for refreshing my memory.
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EJO now a 1994 940T 190K; ex '63 123S; ex '75 245; and ex '81 242GT

That light is a service light, just a reminder to bring your Volvo into a dealer so they can clean out your wallet. It lights up after 10k in a normally aspirated engine and 5k in a turbo. This is NOT the check engine light that will warn you of emission problems.

You can reset the light by removing (and not loosing) the rubber plug in the instrument cluster window and push in the reset button, Use a ball point pen insert and give it a light but firm push since it is a mechanical reset.

Re-plug the hole but don’t get too aggressive when replacing it otherwise it will fall into the cluster.

Proud to say I had never lost a service reset plug!

JavaLion
Thank you I'll do that, but isn't this reset for when the light stays always on?
Mine goes out after 2 to 4 minutes or is that NOP (normal operating procedure) for the Service Light.
Maybe I should read my Owner manual! B-4 asking questions.
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EJO now a 1994 940T 190K; ex '63 123S; ex '75 245; and ex '81 242GT

How to reset is probably not in your manual, hence the shell out the $$$$ at the dealer. It is in the FAQ which is your "best friend" and ever growing.

Reset light, I have driven thousands of miles while that glowed for the first three minutes after a start. (I am not the only one.) Reseting it is out of my mind by the time I get out of the car.

EJO,

It's nothing to worry about. The light is supposed to stay on for a minute or two so you notice it, and then turn off so it doesn't bug you too much while you're driving. It is operating normally, and the previously posted procedure is the correct approach.

Once you reset it, the service light will come on again when the service interval elapses. I find that the service light is useless because I don't generally wait 10,000 miles between maintenance sessions (I operate on multiples of 3,000 miles), -- so I just reset it and forget it. If you take your car to a shop, then you might want to pay attention to the light and make sure your car is up to date on its service schedule.

Good luck,
--
'92 245 5-speed, '92 944 GL auto