'97 Vortec 5.7 K2500 Suburban 'Open Loop' issue

[HotWheelsBurban]

Did you ever get it sorted out?

 

[Supercharged111]

lean to rich sensor threshold voltage(constant)
Test incomplete or dependent test failed



This sounds like an O2 that isn't switching. Did it specify which bank? Any way for you to monitor O2 output?

 

[mr_s]

Yeah, I finally got it sorted a little while ago (think I had another thread and forgot to update this one!).

I replaced the ECU with one from eBay (with the same part numbers). Seems that either a previous owner had the EGR and O2 tuned out of it - after testing everything else, it was the only logical option.

Or as the truck was initially an export to Russia (and made its way to the UK via Morocco!), I wonder if they had the ECU like that from the factory perhaps?

 

[mr_s]

Here's the other thread where I documented everything I tried:

https://www.gmt400.com/threads/check-engine-light-query.47659/