Check engine light?

Engine light not dissapearing I did the service hoping that it will dissapear vvti 2, 7 toyota hilux

2003 Tacoma has only 25,000 miles, never overheated, been sitting alot, very well maintained, oneday engine lu=ight is on & engine is idling rough, as by misfire. All plugs replaced, compression on 3rd cylinder has no compression. How could this occur? And what will be the repair/ cost necessary to repair the engine on this truck?

I just bought this truck and it needs some TLC. While replacing the stock exhaust with larger pipes and a Flowmaster exhaust I acquired a bit of HP and mileage but I also got a frequently lit "check engine light". Is there any way to recalibrate the computer or fool the O2 sensor to keep this nagging light off? The truck runs very well and the scanner shows no other codes hampering the truck. Please help. There are no real mechanics here.

The check engine light shouldn't come on. Does the O2 sensor detect a lean condition? You might want to make sure your exhaust system was welded correctly.

It was welded professionally. However the truck takes a while to detect a lean condition. Is there a dummy sensor available or should I just remove the light bulb. It doesn't hamper the performance but it sure is annoying.

If it detects a lean condition then you have too much air in the system. Even a bad seal of fastening epoxy on the O2 senor could allow air to get by. Did you replace the exhaust manifolds? (Can't weld on cast iron) I have never seen someone weld downpipes and exhaust manifolds because then it becomes a real pain to remove. I wouldn't recommend removing the check engine lamp because you will not know if other problems arise.