what are the best o2 sensors to use on the front with headers? I had changed mine out due to one having insufficient activity and now it throws codes for both insufficient activity no heater circuit codes. Bank1 sensor1 bank2 sensor 2 p0134 p0154 for insufficient activity i had just checked harness and has all power to connector. I had used 114k mile delphis that were used after the cat converter. Im guessing theyre spent to as far as performance goes. So whats the best o2s to get these days? Autozone has 1 year warranty amazon or rock auto or almost half the price but which brand sensors or part numbers are the best to replace for new set? If ordered thru amazon just confirm its in brand packaging and new? Ohm test for 4-14 ohms on the multimeters? AFS75 or delphi, densos?

 

TBH they all suck, and are a crapshoot. Aftermarket sensors (O2 and otherwise) tend to be straight-up garbage, and no matter what brand you get it's going to be a roll of the dice. Delco, Bosch, Delphi, Denso, etc are all pretty equivalent in quality and reliability, and are probably all made by the same 7 year old slave in the same factory in China and just end up in different boxes.

 

Went with new gm ac delco o2 sensor.

 

Afs75

 

I went with afs75 original o2 sensors.

 

[QUOTE=Justin Raney;1604824327]I think i may go with the 30$ AFS75 o2 sensors which are ac delco. I only seen my stock o2s had AFS on them. They look to be a newer style as far as the o2 sensor probe. The tuner recommended ac delco but parts geek told me denso were usually the best. c5diag said he had purchased i think it was Bosch brand that were bad out of the box and returned them for a different set. When testing the o2 sensors you test for 4-14ohm from the heater circuit i think it is or the signal wires? No way to test each signal wire? My harness are good i tested both heater circuits had 12 volts whatever the battery had and both signal wires 4.5-4.9 on each connector so i narrowed it down to old o2 sensors. I did use the bosch corvette rear o2s sqaure style connector because the harness is longer didnt require o2 extension harness on my 98 z28 with slp headers and hooker headers from napa and my 98z28 never had a check engine light. One time when doing the slp headers in 2009 i had hit some of the spark plugs cracking the porceilin and the car ran rough on 4-6 cylinders misfiring took me a while to figure out the issue is 0n ls1 f-bodies the ses light flashes for misfire. Went and replaced the plugs at oreillys i think it was cleared it up and ran like a strong 6 speed 98 z28 ls1 engine.


The ones that were on the car are stock AFS75 one had a heater circuit issue the other had insufficient activity. Rock auto has them for 30$ but a 24month unlimited mileage warranty may be best to purchase from them incase one is bad or goes bad out of the box or whichever. These 114k mile delphis are worse both have unsufficient activity they are on a modded vehicle probably wouldnt throw codes on

I read in the 1998 Service Manual that a "dropped" Heated O2 sensor is considered as a bad O2 sensor. So, I read this as saying that these things are pretty damn sensitive to anything other than very careful handling.

 

I just changed my O2 sensors this past summer, 18 years old/60,000 miles. Anyway, I bought them at the Chevy dealer, and I've had absolutely no issues with them. It might cost a bit more, but I'd like to think you've got a better shot at genuine GM parts at a GM dealer, rather than buying them online in a counterfeit GM box from an unknown source....

 

Amazon is notorious for fake OEM parts

 

They sure are!! I'd NEVER buy any internal engine parts there, I'll tell you that...