Check Engine light

[90GMCJim]

Today I drove the truck in to get the windshield replaced

I just got the car replaced and drove it all day and had no problems. Today going into work I got stuck in traffic and the truck idled for a while in traffic. No signs of trouble until 15-20 minutes in and the check engine light came on. Once traffic started to move I was able to drive and 10 minutes into moving at normal highway speed the check engine light started flashing

Code 42
Code 44

I have electric fans and I ran my ignition wire to the fuse box and bought a fused splice to run to the ignition.
Could that cause 42?

44 is o2 sensor? Should I just replace those? 1 or 2?

Thank you

 

[Wes Harden]

44 is o2 low voltage. This might be caused by a vacuum leak. It could also be sn old worn out o2. They chemical batteries so they do have a life span.
42 is icm related. The tbi distributor were never the most robust. It may be time to replace the ignition control module (icm) cap and rotor.
Unfortunately the whole dist might be worn out. Very hard to find good replacements these days.
As for your wiring not knowing which wire you spliced i can't say. I would encourage you to move it to an open ign hot cavity in the fuse box.

 

[90GMCJim]

44 is o2 low voltage. This might be caused by a vacuum leak. It could also be sn old worn out o2. They chemical batteries so they do have a life span.
42 is icm related. The tbi distributor were never the most robust. It may be time to replace the ignition control module (icm) cap and rotor.
Unfortunately the whole dist might be worn out. Very hard to find good replacements these days.
As for your wiring not knowing which wire you spliced i can't say. I would encourage you to move it to an open ign hot cavity in the fuse box.

For a vacuum leak where should I look? With traffic I’m about 2 hours from home. Should it be ok to drive or tow it?

 

[Blue85]

The AFR isn't affected as much by an intake leak on a speed density system like GM TBI (compared to MAF setups), but it can still cause issues. Most common things would be broken vacuum lines or a throttle body gasket. (BTW, it's important not to overtighten the bolts on the throttle body.) You can also get a leak in the exhaust, which brings in extra oxygen, which reads as a lean condition. The ECM will add fuel (incorrectly) to compensate, but if the allowable range is exceeded, you get the low voltage code. Sometimes those old 1-wire sensors will drop the reading if they get cold from idling too long (or if they're old), which will set the code, but will still do OK under normal driving.

Personally, I would not be afraid to drive it, as long as it seems to be running OK. The thing with these codes is that you don't know when they were set. A code 42 can be present just from somebody having set the timing and not clearing it. You could unplug the ECM or disconnect the battery to clear the codes and see what returns.

https://ck5.com/forums/threads/tbi-trouble-codes.240425/

 

[90GMCJim]

Thank you for that. It sat for 2 hours then I drove it to the windshield place and no codes. I was in bumper to bumper traffic for close to 25 min

 

[gmbellew]

Codes are only stored for around 30 starts.

Code 42 does get set if you unplug the EST bypass Or if there is a short to ground in the EST bypass. Or if there is an open or short in the white EST wire in the ICM harness. Or stray voltage to any of the ICM wires from plug wires being too close or other wiring hackery. Could also be an ICM that is failing. An open ground in the ICM Low Reference (blk/red) will not set code 42, but will show up in a jumpy tachometer.