AEM Air/Fuel gauge seems to be non responsive

[Kern Dog]

Years ago on the advice of a fellow car guy, I installed an air/fuel gauge. I was having detonation issues and thought that the gauge could help me tune my way out of the problem. Over the years, I have enjoyed having this gauge because it showed in real time what was going on. You could see it move around with even a 1/4 turn of the 4 corner idle mixture screws.

Lately, the readings have stayed in the 14.4 to 14.8 range which would be great if I was running 100 % pure gasoline but I'm not. We have (Up to 10%) ethanol here so the numbers should be in the high 13s at idle and cruise.
The numbers have stayed in a narrow range lately. Before, they would run into the mid to high 11s at WOT. They would be real lean at cold idle.
I'm curious if the lazy response I'm seeing means the oxygen sensor is going bad or if the gauge itself is to blame.
Where are the gurus on this stuff ?

 

[1 Wild R/T]

Cheaper than Summit
https://www.amazon.com/Bosch-Automo...6f139758e6addcc250a552a&qid=1758864754&sr=8-3

Much cheaper than Amazon but seems to cheap to not be a Chinese knockoff

https://www.ebay.com/itm/405541440304?chn=ps&_trkparms=ispr=1&amdata=enc:1sWSC1f6BR8ezQqre3bVk2A34&norover=1&mkevt=1&mkrid=711-173151-913341-5&mkcid=2&mkscid=101&itemid=405541440304&targetid=2437617225824&device=c&mktype=pla&googleloc=9032278&poi=&campaignid=22904786827&mkgroupid=182643131263&rlsatarget=pla-2437617225824&abcId=10415532&merchantid=5623123187&gad_source=1&gad_campaignid=22904786827&gbraid=0AAAAAD_QDh9ZB3TmLqXO29yUvACokzBjD&gclid=Cj0KCQjw0NPGBhCDARIsAGAzpp3R3bRvNHs1iWgIMmpccU2uap10CDnJKOUDuiIse7a0ku7hziQi_NYaArDeEALw_wcB

And yes your sensor has likely died...

 

[Kern Dog]

My bonehead logic has me thinking that a dead sensor would show ERR or a blank display. I bought this gauge well over 10-12 years ago.
I'll drive it and see if the numbers move around at all.
The car runs great. No smoke, no stumble, no detonation. It rarely ever smells like fuel either.

 

[Doorkicker]

O2 sensors can have issues with contamination and cause what you're talking about, especially after a decade. here are the ones I use as replacements.

 

[dan juhasz]

Yes that sensor is getting lazy. I have the same gauge. The o2 survived about 200 miles as the car uses 100LL. So I expected it to become contaminated and develop slow limited response. But it was a big help in getting the six pack set up.

 

[Frank Mopar]

Take the sensor out and hit it map gas until it’s glowing. All clean and ready to reuse. This works on spark plugs too.

 

[Charlie Brown]

I have an AEM gauge installed. It works well, but the supplied Bosch sensor failed almost
immediately. AEM would not come good for it, even though gauge was still under warranty. An internet search confirms that Bosch sensors are problematic and are replaced often. I replaced my sensor with a Denso unit and have had no further issues.

 

[dan juhasz]

I have an AEM gauge installed. It works well, but the supplied Bosch sensor failed almost
immediately. AEM would not come good for it, even though gauge was still under warranty. An internet search confirms that Bosch sensors are problematic and are replaced often. I replaced my sensor with a Denso unit and have had no further issues.

Do you recall the Denso part number

 

[Bird 426]

When my sensors fail, the gauge usually has 3 red lines across the bottom. Sensors are cheap from China, about $30. They last as long as the orginal Bosch did. I kill them from being too rich.

 

[Kern Dog]

Today I fired it up and the numbers did move around some but not like they used to.
Before, the engine had to be up to operating temperature before the numbers would stabilize at idle. Today it fluctuated between 14.5 to 15.2, then settled back into the mid 14s even when I rapped the throttle. When started up, it did read the 111, 222, 333 etc until settling on the actual reading.
This isn't crucial at the moment since the car is running so good. I still would prefer to have everything functional.

 

[Charlie Brown]

Do you recall the Denso part number

Denso 234-5136 Got it at Rock Auto. Cost was about $50 a few years ago.