98 GTB Legacy Check Engine Light & Rough Idle

Hey guys,

 

My 98 Legacy check engine light came on today randomly.. I drove it for about half an hour, parked up, and when I came back a couple of hours later I started it and the check engine light remained illuminated, and it idled rough.

 

I popped the lid, checked the air flow sensor was still in correct, pulled it out and the engine shut off so that must be working fine. Plugged it back in, restarted, check engine light still there and still rough idle.

 

So I drove it for a bit... every time I stopped and rpm dropped to idle you could feel something was wrong, but when it was driving and at revs above 1000rpm there was no difference at all.

 

So, for now, I'm driving it as normal because it still runs fine....

 

Question is, what do you think is causing the check engine light to stay on? And am I fine to just keep driving it like I am.....

 

Cheers

What code are you getting?

O.

The check engine light signals about 400 different codes so it being on doesn't tell us much. This is also not 1991 when codes were difficult. Everyone has the ability to read engine codes for the cost of lunch.

 

If we had a code to work with we would know if your problem is serious, urgent, or drive as is.

 

Maybe your problem will wash a cylinder and you'll take the car to the salvage yard in a couple weeks. Maybe you are making .0001% more emissions and can drive it that way for years.

 

I really like and use regularly https://www.amazon.com/obdator-Bluetooth-Scanner-Automotive-Diagnostic/dp/B074DWH8JR/ref=sr_1_5?dchild=1&keywords=elm327&qid=1618175126&sr=8-5

 

If you drive about every day you can plug this in and leave it forever. You pair it with various apps on your phone and done. I use TorquePro, but the free version Torque would get you everything you need.

I dropped into my local subi shop today, code said it was the MAF. So I've taken it out and given it a good clean out with CRC MAF cleaner, still no success. I'll try again tomorrow and then head off to the wreckers and see if I can get a good 2nd hand one.

I'm not familiar with the "it's the MAF" code.

 

I know about the P0100 MAF circuit malfunction, the P0101 MAF implausible data, the P0102 MAF input low, the P0103 MAF input high, the P0104 MAF circuit intermittent. Most of those describe wiring problems rather than a problem with the sensor itself.

 

I do agree that the quickest way to figure this out without tools is to swap one or two in from a junkyard if they don't want a lot of money for it.

Fixed. Picked up another air flow sensor from the wreckers. Works good as new.

Cool!

 

Thanks for telling us rather than just vanishing. It does help to document what works and what doesn't work.