Check engine light-scanner says O2 sensor

[toneydoc]

Well after 136k miles, my engine light came on. I stopped by OReillys and an Oreillys employee scans it and tells me it is an oxygen sensor. He asks me what the Jeep is doing and I say it is running fine like always. He proceeds to say that it is a fairly cheap fix, etc.

I drove home with no issues. Today I drive it again and no issues at all.

What do you guys think? What is the worst thing that can happen with a bad oxygen sensor.

Replacement seems easy enough. Just curious as to your thoughts.

 

[eljefino]

Well we need the code, there are a bunch of o2 related codes.

There's one though, PO133, that reads lazy o2, that's pretty cut & dry.

As the o2 reports any fuel mix drama, it often falsely gets indicted for other issues.

Worst thing that can happen is you'll waste gas, run worse, poison your cat, and a "real" problem will go unnoticed since you already assume your CEL is innocuous.

 

[toneydoc]

I think he said 021 code

 

[eljefino]

Ah for a 94:

21 - Upstream oxygen sensor response slower than minimum required switching frequency. Upstream oxygen sensor heating element circuit malfunction. Downstream oxygen sensor heating element circuit malfunction. Downstream oxygen sensor input voltage maintained above the normal operating range. Oxygen sensor voltage too low, tested after cold start. (Upstream or Downstream) Left oxygen sensor input voltage maintained above the normal operating temperature.

Surprised Oreilly's has an OBD-I scanner, but good on them.

Does really point at the sensor.

 

[tinmanSC]

poor running oxygen sensors normally don't produce any issues you can feel while driving (but they can, I suppose?). At least I've never experienced any issues in modern (or modern-ish) cars with O2 issues. The primary issue would be poor fuel mileage. Long-term it can have deleterious effects on catalytic converters and engine parts, but like I said, that's long-term. If the computer is warning of an O2 failure, it should be replaced even if you don't experience noticeable issues. You'll need an special tool, an O2 sensor socket to remove it and to install the new one. I recommend the low profile ones, easier to deal with.

 

[SrDriver]

Not expensive fix. Big + will be better fuel economy.

 

[eljefino]

Originally Posted By: tinmanSC
You'll need an special tool, an O2 sensor socket to remove it and to install the new one. I recommend the low profile ones, easier to deal with.


Sometimes you can get a 22mm or 7/8 wrench on 'em, depends on the manifold and heat shields.

 

[Kruse]

Originally Posted By: eljefino

Sometimes you can get a 22mm or 7/8 wrench on 'em, depends on the manifold and heat shields.


+1. Quite often the shadetree mechanic doesn't need the special O2 socket. As noted, use a common wrench and simply cut off the wires of the O2 sensor to slip the wrench on. The last O2 sensor that I replaced was removed with a regular deep socket.

 

[toneydoc]

Those thoughts were the same ones I was having. Appreciate input on sensor removal. Ill pick up a sensor and get after it one fine day.