O2 sensor replacement - Check Engine Light...

[gginnj]

The CEL on our 2004 vibe was on, per the codes and a mechanic said it was the O2 sensor upstream. I replaced the O2 sensor with an Amazon purchase - forget the brand off hand. The previous owner said he replaced it also about 6 months prior to our purchasing it. I did note that the one I removed looked different - it only had one row of holes, whereas the one I put in had about 4 rows of holes (not sure if that makes a difference). The plug was the same, the overall length of the sensor that goes into the exhaust was the same length, just the number of sampling holes was different. Of course
the previous owner could have replaced it with the incorrect sensor. How many sampling rows should the upstream sensor have?

I replaced it, if it was the problem, should the CEL go off right away? Ours did not so I cleared all the codes, and so far the CEL has stayed off, although I haven't rechecked lately to see if all the sensors are reporting in yet - it's been close to 100 miles so I'm hoping for the best at this point.

Thanks

[vibrologist]

Don't worry until the CEL comes on again. Then post the codes here.

[gginnj]

Does it matter how many sampling ports are on the oxygen sensor? Would the old one having 1 row vs the one I used having 4 have any significance other than different manufactures?

As for the old code, I forget which one it was - but it was only 1 code - and it was specific to the upstream o2 sensor - which was a breeze to replace on that engine. Didn't even need to remove the heat shield as some as suggested - I used the crows foot socket which was short enough to fit between the shield and the firewall. If I was using the longer socket then yes, I would have had to remove the shield.

[vibrologist]

I don't think it matters how many ports there are on the sensor. It matters that the gasses hit the sensor and that the sensor reacts to it.

The term O2 specific codes is way to vague. We need the actual code. For example P0171: System lean, bank 1. That is a code derived from data coming from the oxygen sensors. The most likely cause is a vacuum leak.

So: Don't worry until the CEL comes on again. Then post the codes here.

[Derf]

Since you already paid for and installed the O2 sensor, your committed to what you have. Until your vehicle displays a code, their is no way to advise what action to take.
When I replaced my O2 sensors, there were many aftermarket options, but they all lacked solid reviews. I went with OEM, since it had an established track record.

[gginnj]

Just a followup - the CEL came back on again after about 90 days. I pulled the code but it wasn't o2 related - rather MAF related.P0170
I wasn't sure if it was fuel related - since most stations are now running with winter gasahol - I just reset the code again only because
I needed to get the car inspected, which you can't do with an active CEL in NJ - drove it a couple hundred miles - rescanned and all systems
were reporting in - so got the car inspected - passed fine.

I pulled the MAF sensor - it looked clean - but I sprayed it down anyway. If the CEL p0170 comes back, should I just replace the MAF sensor?
I also replaced the air filter just in case, but it didn't appear that dirty - but figured it couldn't hurt, it's been over 6 months since it was last changed, and have had a few long trips.

as a side note, how often should you clean the MAF sensor?

[vibrologist]

Please discard the notion that a code is pointing to a particular part failing. The codes only point to certain conditions that are out of parameters. it is the mechanic's job to find out how this happened. That's why you need a mechanic with grey matter up there.

I bet you have a vacuum leak.

Read this: https://www.obd-codes.com/p0170

[gginnj]

I read that about the vacuum leak also, but it doesn't act like it has a leak - or not one significant enough
to cause rough idling or hesitation - the rpms stay pretty steady. it took almost 3 months to come back,
and when cleared again, so far it's been almost 2 weeks. I would think if it was a vacuum leak it wouldn't
be so long in between detections.

Any particular places to look for the leak? most common areas?

[vibrologist]

The code gets only set if the same malfunction is detected 2x in sequence. There may be a leak that the computer is able to compensate for most of the time, but not all of the time.

The most common cause of vacuum leaks is a deterioration of the intake manifold gasket. If you still have the original gasket the odds are darn good for that.

You can try and spray some carb cleaner around the intake manifold gasket while the engine idles. If you notice a change in how it runs you have detected a leak.

[gginnj]

I'll have to try that another day - or if the light comes back on.

We have noticed a decrease in the RPMS when first started since I cleaned the MAF sensor, and it seems
to run a little smoother. Maybe just coincedence - but for now - I'll try not to find something that isn't
asking to be found! at least not asking loudly!