Trouble Code 42

Hi guys. I have a 92 buick century 3.3 l. The wires, plugs, O2 sensor are new. The check engine light is on. I checked the code and its code 42. That is the by pass or electric spark testing curcuit. The circuit consists of the ecm, crank sensor, cam sensor, and I think that is it. If anyone could help me and point me in the right direction to figuire out how to find out what exactly is causing the problem. The car idles good with a slight vibration but as soon as you put it in drive it drops about 500 rpm and starts running ruff. It almost stalls. The car has sat for a year and a half. I just purched it. I have changed all the fluids, brakes and brake lines, fuel sending unit and battery. All I need to do now is get it safetyed after I fix this problem so any ideas or help will be greatly appreciated. Thanx Aaron

Hi guys. I have a 92 buick century 3.3 l. The wires, plugs, O2 sensor are new. The check engine light is on. I checked the code and its code 42. That is the by pass or electric spark testing curcuit. The circuit consists of the ecm, crank sensor, cam sensor, and I think that is it. If anyone could help me and point me in the right direction to figuire out how to find out what exactly is causing the problem. The car idles good with a slight vibration but as soon as you put it in drive it drops about 500 rpm and starts running ruff. It almost stalls. The car has sat for a year and a half. I just purched it. I have changed all the fluids, brakes and brake lines, fuel sending unit and battery. All I need to do now is get it safetyed after I fix this problem so any ideas or help will be greatly appreciated. Thanx Aaron


Ah Haa.. I had the dreaded Code 42 too (hehe). Anyways let me start with SYMPTOMS: ( I had):

~ an occasional start after constant cranking and killing the battery over and over

~ getting spark to the plugs

~ NO fuel injector spraying (VERY IMPORTANT)

my ECM didnt show any codes saying that something was wrong with it (I think a code 55 for GM)

So, I went to the salvage yard, bought a CAM SENSOR for $5 and and an ECM for $25 (1990 Buick Lesabre VIN:C ECM#1228253).

Next, installed the CAM SENSOR after comparing CONTINUITY readings on the one that came out of my car VS. the salvage yard's (BTW, I made sure that I got parts from a WRECKED VEHICLE -- great sign that it was probably running).

I noticed that the right-most terminals inside of the sensor had NO continuity on them (right-most meaning having the sensor's connecton clip for the harness is faced upward). However, the two terminals on the salvage yard sensor had SOME continuity (and resistance). Things looked promising.

See, the CAM SENSOR is part of the EST system and it also signals the computer to fire the FUEL INJECTORS.

Next, I replaced the ECM.

The car sprang to life immediately! I let it warm up to normal temp, switched it off, grounded the diagnostic terminal on the ALDL and no more Code 42! Gone! and called the guy to tell him to come get his car, it's ready.