I'm Back! (P0421 CEL Code)

[Fummins]

They seem to be hit or miss. The obd gps things we use at work caused problems, we recently tried a different brand/company for a few months and they worked perfectly fine.

[Navysteveo87]

CEL came back on today. Gonna drill out the top to make the hole a little bigger so more air can get to the O2 sensor.

[7milesout]

Edfrwws Car CEL Fix O2 Sensor Check Engine Light Eliminator Adapter with Mini CAT.

ELM 327 BT OBD-II connector.

Torque-Lite app.

[Navysteveo87]

*Update*

I couldn't drill out the top of the O2 spacer (on the right) so I purchased a different one with a larger hole on top.

https://www.walmart.com/ip/Car-Oxyge...lter/217383518

Cleared the codes and now we wait and see if the CEL comes back on or not.

This is it...if it does come back on i'm not trying any other "hacks" to keep my CEL off.

I'm currently getting 39 mpg and it doesn't seem to affect anything else on the car since it's just the downstream O2 sensor.

[7milesout]

Nice update. That one on the left, looks like the one that works on my son's car. It's still working. But, as noted, it's a different car. Could yield entirely different results.

I'm on the verge of pulling off the 2nd cat and modifying the rest of the exhaust (except the resonator) on my car. Just for squirts n giggles.

[Navysteveo87]

7miles,

I thought your son's car had the spacer with the honeycomb material built into it like so...

https://www.walmart.com/ip/2-Pcs-Car...eel/6062963133


The spacer I bought has no material on the inside. I wanted to get more air to the O2 sensor so I went with a spacer that has a larger hole on top so I can avoid code P0137 (oxygen sensor low voltage). Hopefully this works

[7milesout]

I couldn't tell you what is really inside of it. But it looks like the one on the left in your picture and SUPPOSEDLY it has some amount of catalyst material for gases to pass through before they get to the sensor. That's what the description of it said.