Service Engine Soon...

This light come on last week so I pulled the codes off the internet and found that error 12 and 23 were coming up. I don't know why error 12 would be happening, that's battery or computer has been recently disconnected. As for error 23, bad o2 sensor reading, that I could understand as they fail sometimes...

Anyways, I took the battery terminals off and cleaned them up, then re-connected. The Service Engine Light disappeared for about a day, then came on again with the two same codes...

Anyone know why this is happening??

Thanks

sounds like the O2 sensor is on the way out,and code 12 is there almost always and usually for no reason.

How many O2 sensors are there and how do I know which one it is?

I know I had three on my last van, a Mercury Villager...(CRAP)
Does anyone know how many on 99 Voyager??

Might want to double check the code. I know Haynes manuals aren't the bible of maintenance manuals but it says code 23 is an intake air temp sensor problem. This is out of a 96-98 manual.

If you meant code 21 there should be 2 sensors. The upstream 02 sensor sits on top of the exhaust manifold on the back side of the engine. The downstream sensor sits either on or just aft of the cat converter. An OBDII scanner will tell you which is bad.

I agree with the others. I always have a code 12. Just ignore it.