Dreaded Catalyst Monitor 02 Tacoma

I had a hell of a time getting my catalyst monitor to set before my last smog check, did the FSM drive cycle numerous times and a 1000 miles of driving, no dice. I ended up putting a can of Cataclean in the tank and taking it off-road in 4lo, after 5 minutes in 4lo they set green.

If your sensors were the issue you'd have a CEL on

Weird that yours isn't after the new cats, are they aftermarket or? 50 state legal ones?

cheap cats have less of the material in them to filter the emissions and might not satisfy the sensor thus not satisfying the monitors

 

@jjnicolas No codes, just the Cat Monitor reading INC.

I took your advice @02hilux and reset the OBD2, and have driven it 100 miles, doing a basic drive cycle twice as well as the tedious Drive Cycle #4 for Cat Mon - 4 times. Oxygen/fuel sensors cleared, Cat monitor is still reading INC.

I tried Cataclean when this issue first came up last month. I have a second bottle I’ll most likely use cuz it wouldn’t hurt. My temporary AZ plate expires at the end of this month. Gonna see if the CA DMV can issue me a temporary plate until I can get this issue resolved (Purchased this truck in AZ, need to get it registered in CA, hence the smog)

Appreciate the advice!

 

Might be worth it to remove your cat to verify if the "honey comb" is still in tact and if you're able to see through it if you haven't.

3 months ago, I "cleaned" my 03 corolla cat after all attempt failed to get the CAT monitor ready for CA smog. I changed the oxygen sensor a few weeks prior, hoping it will help, it didn't. This was the last option before buying a new cat @ $1200. Some folks will probably laugh saying "YOU CAN'T CLEANED A CAT" but it worked for me. So jokes on you, lol.

1) I soaked the entire cat with Dawn dish soap and water solution overnight. Use the garden hose and nozzle to thoroughly spray the soapy solution.
2)I than soaked the cat with straight Simple Green in a large tray for about an 3 hours. Use the garden hose and nozzle to throughly clean it out.
3) I than soaked the cat with some Walmart brand vinegar for an hour. Again, using the garden hose and nozzle to throughly spray out any vinegar solution.

Drained it completely and left it standing vertical for several hours to drain as much water out as possible.

Reinstalled the cat with all new gaskets and took it for a drive on the highway for about 20 minutes (traveling 65mph with cruise control) and got off the highway for in town, stop and go traffic. About 15 minutes later, while driving back home, I pulled over and all the monitor were green including the CAT. Went straight for a smog after that.

 

Dawn dish soap is like Marvel Mystery Oil, shit works to clean everything.

 

Sh1t do wonders

 

@02hilux Thanks for the rec regarding removing/soaking the cat.

Will removing the cat trigger any codes? Just want to know what to prepare for once I remove the cat to soak it. I am picking up new gaskets beforehand.

This will be my first time removing a cat from any vehicle so I want to do it right the first time.

Thanks!

 

No code as long as you don't use the vehicle when the cat is off

 

Without cats in it will definitely throw a P0420 catalyst inefficiency code, that's as inefficient a cat system as you can get...

But yeah only if you start it up. Even if you do, assuming cleaning it did the truck, the monitors will go green and the code will go away

 

Update: Ended up being a leaky O2 sensor. Wasn’t enough to throw codes but was interfering with the cat monitor.

Passed smog.

Thanks again for all the suggestions!

 

Just so others finding this thread in the future can follow your process- When you say "leaky O2 sensor", do you mean the gasket around the sensor had failed? What lead you to this result?

 

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