thought i'd turn to you guys to see if anyone out there with the same vehicle might have some new insights.

i recently bought a 98 blazer 4X4 with 129.000 miles. it has a rough idle/slight vibration that seems to get worse sometimes the longer i drive it. when i bought it and ran diagnostics on it i got three codes-one for the egr, a p0135 02 heat sensor malfunction and a random misfire. cleaned the egr and the misfire and egr codes have disappeared.

since then i have replaced the O2 sensor. first with a bosch and then with an ngk. i also pulled a harness that goes from the 02s to the pcm and switched that out as well. there is continuity on all the wires. i even pulled the ecm opened it up to look for any visible signs of damage but couldn't find any. found three ground wires all connected to the chassis. can't detect any vacuum leaks. the 135 code keeps coming back

the engine has already been replaced with a low mileage one (not sure when). i did a full tune-up-oem plugs, cap, rotor and wires. replaced fuel filter and checked air filter, pcv valve and had a fuel injection cleaner ran on it.
should i even worry about the po135? does that really even make that much of a difference? wondering if maybe the injectors are dirty or leaking. any suggestions would be appreciated

oh i also checked the motor transmission mounts. they seem to be good

 

Welcome from New York. Watch your double posts, use the edit button to add to previous post,. Also, post your questions in the correct section.

 

*Moved to 2nd Gen Tech* - Please read the forum descriptions and choose the section based on the nature of your post. The New Member Area is for new member introductions. Technical questions are much more appropriate one of the technical sections.

Have you tried putting P0135 (P ZERO 135) into the search box at the top? There is a lot of useful information out there!

 

oops. sorry about that.

so i downloaded the trouble shooting guide on P0 135 and it appears that i have a bad ground somewhere. i found three grounds to the chassis-two off of the negative battery terminal and another close by it. looks like there are only three as best as i can tell from the diagrams in my hayes manual. where could i find wiring repair diagrams specific to the 02 heater sensor?

 

Hello I am having the same issue with p0135 2000 blazer 4x4. I put in a new o2 sensor and all so re did the grounding to the chase and did and drive cycle same issue. Do you have any pics of where the wires goes so can trace them down or where the grounds go so i can check them. Did you find a wiring diagram that you can share? Thanks..

 

Spider injector needs cleaning or replacing. There is an upgraded version
n

 

P0135 is a problem in the bank 1 sensor 1, (driver side, closest to the manifold) oxygen sensor heater circuit. Has nothing to do with the injectors. Follow this flow chart: https://blazerforum.com/forum/diagno...plained-26610/

 

I am getting P1035 and i add a new ground wire. Cleared the code and it comes back.
I took out a working o2 sensor and put it in bank 1 sens 1. I left bank 2 sensor 1 EMPTY (YES IT WAS LOUD BUT IT WAS A TEST) I drove the trunk for 7 miles. Engine light came on and i re scanned and guess what still p1035 and no error code for the missing o2 sensor. How can this be.

 

Follow the flow chart in post #7, (there are two pages). If you follow it exactly as written, it will find and fix the problem, guaranteed.