My check engine light just came on just as I turned 140,000 miles on my 1990 Mazda B2200. Everything seems fine but the light came on just as the miles went from 139,999 to 140,000. Is this for a standard check like I have read other places or could be a problem?

 

There is a set of black and white wires under the driver's side dash. I had to swich them around when my truck hit exactly 80k, I think it is supposed to have been to get the truck to the dealer for an emissions check. I think that whatever wire is plugged in, unplug it and replace it with the other. I remember that the shop manual or owners manual had more info.

 

I had an Emissions test done yesterday before the light came on at 139,950 miles and everything passed fine. So hopefully it is just that.

 

it is set to light up at 60,000 and 120,000

 

Every certain # of miles the check engine light is programmed to go on. I have a b2600i and it goes on every 60,000 miles exactly. U can check a manual. It's only one wire to move right next to another position under your dash near the steering column- very simple or you can give a mechanic $ 75 to do this or you can wait until ( my case ) 120,000 miles until it goes off. I waited.

 

At 60K miles, 80K, 120K, etc., the Malfunction Indicator Light will come on, supposedly so you get dealer to check emissions but more likely so they can try to sell you a timing belt replacement. By the way, do get the timing belt replaced every 60K miles, and maybe get the water pump changed at the 120K point along with it, as it's an internal water pump, behind the timing belt, and mine started leaking at that point, so it's a big labor savings $$$ to do both at once. The Malfunction Indicator Light is re-set by swapping a wire push-on connector under the dash, driver side, right next to the firewall; it's hard to see, lie down and look up, there will be a bare connector, just swap it, then swap back next time the light goes on at that set interval.

 

Yeah, I did change the wire and the light went off. I guess if there was a real problem it would have come back on? The truck is running great. Thanks for the tip. Also when I bought the truck I took it by to a friend who it a tech. He said it looks like my timing belt will need to be changed soon since it is adjusted almost all the way out. Guess I need to get a quote on that.

 

Unfortunately can't tell the condition of a timing belt that "looks OK". The tightness is not through an adjustment, but by tensioner. Change it if you don't KNOW how long it's been used.