Lesson learned: don't cheap out

[Anduril]

Wife has been complaining that she's been filling up her car a lot more than normal lately. So we fill it up and burn through a tank and she's only getting like 21-22 mpg which is absolutely terrible and worse than my truck. Bottom line, it turns out that the culprit was the cheapie $10 RockAuto special O2 sensor I installed to get the thing to pass smog about a year ago. This time I went with a proper $35 ACDelco sensor and she got 27 and change mpg on the last tank. What's amazing is that there were absolutely no drivability issues or CEL, and the car passed smog with flying colors, but it sure drank gas. Wonder how many times we've paid for that cheap sensor in wasted gas.

 

[Quattro Pete]

Good catch.

I'm pretty sure the OEM O2 sensors on my car are also way past their prime and impacting fuel economy, yet they are still not outside of the limit enough to trigger a CEL.

 

[Anduril]

What's interesting is I drove it with one of those OBD2 scanners attached that calculates MPG and it was reading around 30 (which that car might be able to get, downhill, foot off the gas, at 55, no thanks to the 3 speed auto trans), but using the trip meter + gallons filled gave closer to 20. I thought those things were based on fuel flow, which is also measured by the scanner, so I don't know what gives there.

 

[09_GXP]

A lot of OBD2 readers will need to be calibrated to make up for the error in the readings. If you read a ScanGaugeII manual it has a procedure on how to drive and fill for the first few tanks to get more accurate readings.

 

[blupupher]

Yup, O2 sensors are one thing I always get OEM, regardless of cost. Most engine sensors as a matter of fact I choose OEM.

 

[funflyer]

I only order oil filters from RA because I use them to filter my parts-cleaner fluid and they are dirt cheap. I would never buy anything else from RA. There's an internet full of complaints against them along with over 2000 listed on the BBB.

 

[Bgallagher]

I got a question, I purchased a Denso O2 sensor and was meaning to put it in my Equinox. How do people feel about Denso brand or is everything kinda [censored] except for OEM?

 

[Bottom_Feeder]

Originally Posted By: Anduril
Bottom line, it turns out that the culprit was the cheapie $10 RockAuto special O2 sensor

What brand was it?

 

[Bottom_Feeder]

Originally Posted By: Bgallagher
I got a question, I purchased a Denso O2 sensor and was meaning to put it in my Equinox. How do people feel about Denso brand or is everything kinda [censored] except for OEM?

Denso sensors and plugs are excellent. It just depends on what came OEM and if your ECU 'likes' it.

 

[Anduril]

Originally Posted By: Bottom_Feeder
Originally Posted By: Anduril
Bottom line, it turns out that the culprit was the cheapie $10 RockAuto special O2 sensor

What brand was it?

Ultra Power. Never heard of them before but I bought it because it was $10. Now I know why.

Originally Posted By: Bgallagher
I got a question, I purchased a Denso O2 sensor and was meaning to put it in my Equinox. How do people feel about Denso brand or is everything kinda [censored] except for OEM?

No idea. I've at least heard of that brand before. I just figured I might as well get what came with the car because that's what has worked for 17 years now.

 

[Wolf359]

Originally Posted By: Bgallagher
I got a question, I purchased a Denso O2 sensor and was meaning to put it in my Equinox. How do people feel about Denso brand or is everything kinda [censored] except for OEM?


I think Denso is OEM for many car makers. OP might have just gotten a bad no name sensor, I've gotten $25 Denso sensors from Rockauto before, gas mileage was slightly better, maybe just by 1 or 2 mpg.

Best way to really tell with these things is to go to the car forum of your particular car. There were certain things that were better as OEM and certain things that didn't matter whether it was OEM or not. Basically sometimes aftermarket is better as they fix the short cuts OEM makes and sometimes aftermarket takes shortcuts that OEMs don't make.

 

[SwampSurvivor]

Originally Posted By: Quattro Pete
Good catch.

I'm pretty sure the OEM O2 sensors on my car are also way past their prime and impacting fuel economy, yet they are still not outside of the limit enough to trigger a CEL.


The sensors on my Jeep are well past their prime. However, the cats are completely dead; there's very little voltage difference and it smells like they are. I did have to replace one sensor, but I'm a bit worried if I replace the upstream sensors I'll get a catalyst code because the computer will finally realize they are dead.

 

[Anduril]

Pretty sure the upstream sensor controls the engine and the downstream one checks cat efficiency. You could save the old upstream sensor, replace it, and put it back in if you get a CEL.

 

[Wolf359]

Originally Posted By: Anduril
Pretty sure the upstream sensor controls the engine and the downstream one checks cat efficiency. You could save the old upstream sensor, replace it, and put it back in if you get a CEL.


That's pretty standard on most cars. It's the upstream one that does all the switching and hence wears out. There's not much going on with the downstreams as it's not supposed to change much if everything is fine. Went over 200k on the original downstream ones and had to change up upstream ones at a little over 100k.

 

[sleddriver]

That's a critical part to go cheap on. So are other engine sensors.

I wish I could purchase a quality Bosch O2 sensor for $35....

 

[JMJNet]

I have always replaced the one in my cars with Denso Air Fuel ratio sensors (front) or O2 sensors (back).
Of course, all of them have been Toyota and Denso are the OE for them.
They are not the cheapest but has been good with it, never went wrong.

I have used a Bosch once in a 90s Altima but that was the OE for them at that time.

 

[HerrStig]

Originally Posted By: funflyer
I only order oil filters from RA because I use them to filter my parts-cleaner fluid and they are dirt cheap. I would never buy anything else from RA. There's an internet full of complaints against them along with over 2000 listed on the BBB.
And how many SALES did they make in that time?

 

[slacktide_bitog]

Denso and NTK sensors are also good

 

[UltrafanUK]

Very surprised that you did not get a CEL, so I would be inclined to see if the CEL light works. It should be lit after the keys are turned on until the engine starts, just like the other warning and caution lights.

 

[pbm]

Do most of you change your O2 sensors at a certain age/mileage or do you wait for a CEL?