MR2 Roadster Owners Club

The Workshop => General => Topic started by: Benlake on March 25, 2019, 14:12

Title: P0420
Post by: Benlake on March 25, 2019, 14:12
Hi does anyone have a work around for P0420 cat system effiency error. Ive read about removing the code, plug in a transister to trick the sensor and plug in an o2 conditioner / unfouler.
Does anyone know easiest way to get rid of the error I dont think it is doing amy harm (and was expected!) but I would like to clear it so I can notice other errors? Thanks.
Title: Re: P0420
Post by: shnazzle on March 25, 2019, 14:15
What's the reason for the code?
Is it something you're expecting and trying to work around, or is it an unexpected code? If so, I'd definitely try to address the problem.
(exhaust leak, vacuum leak, faulty o2 sensors, etc

If it is expected, you can get an o2 sensor extension. It takes the senser out of the flow a bit making it less likely to read out of tolerance.

Bear in mind that in Toyota's the post-cat sensor does affect fueling.
Title: Re: P0420
Post by: Benlake on March 25, 2019, 14:24
Cat is missing thats why I was expecting it to be unhappy, I did think the sensor pre cat did the fuelling so wasn't anticipating that would be affected although I could be wrong.

I have plugged both sensors into the rogue mid pipe.
Title: Re: P0420
Post by: Benlake on March 25, 2019, 14:49
Do you know where can you buy the extension you mentioned?

Now I am worried about the fuelling too!

I was hoping to avoid an aftermarket ecu.
Title: Re: P0420
Post by: shnazzle on March 25, 2019, 15:29
Ah! Without any cat it all becomes a fair bit easier.

The reason that the post-cat adjusts fueling is to keep the cat happy and work efficiently. If there's no cat to keep happy then that makes the job a lot easier :)

Any M18x1.5 o2 sensor extender will do.

Alternatively wire in an o2 sensor simulator. Basically it returns an oscilating "perfect" signal from the cat to give a permanent thumbs up to the ecu
Title: Re: P0420
Post by: Benlake on March 25, 2019, 15:59
cool will try the extender. Thanks
Title: Re: P0420
Post by: Dev on March 25, 2019, 15:59
Quote from: shnazzle on March 25, 2019, 15:29
Ah! Without any cat it all becomes a fair bit easier.

The reason that the post-cat adjusts fueling is to keep the cat happy and work efficiently. If there's no cat to keep happy then that makes the job a lot easier :)

Any M18x1.5 o2 sensor extender will do.

Alternatively wire in an o2 sensor simulator. Basically it returns an oscilating "perfect" signal from the cat to give a permanent thumbs up to the ecu

Not exactly.  All the post cat sensor does is report that the cat is working as intended. It will have no bearing on the fueling and if the CEL is tripped it will not place the car in limp mode.

The reason why the fouler trick works is because it distances the 02 sensor just enough to fool the ECU. 

If you have P0420 cat system efficiency error its not as simple as getting an anti fouler.  There is a good chance that the catalytic converter is partially blocked causing a slightly restricted exhaust that would be bad for the engine. 
I had this happen to me and lived with resetting the light for a few months until I was able to find a used down pipe. After the install of the new component I picked up lost power.

Its advisable  to buy a good low millage catalytic converter with health flex sections.
Title: Re: P0420
Post by: shnazzle on March 25, 2019, 16:04
Quote from: Dev on March 25, 2019, 15:59
Quote from: shnazzle on March 25, 2019, 15:29
Ah! Without any cat it all becomes a fair bit easier.

The reason that the post-cat adjusts fueling is to keep the cat happy and work efficiently. If there's no cat to keep happy then that makes the job a lot easier :)

Any M18x1.5 o2 sensor extender will do.

Alternatively wire in an o2 sensor simulator. Basically it returns an oscilating "perfect" signal from the cat to give a permanent thumbs up to the ecu

Not exactly.  All the post cat sensor does is report that the cat is working as intended. It will have no bearing on the fueling and if the CEL is tripped it will not place the car in limp mode.

The reason why the fouler trick works is because it distances the 02 sensor just enough to fool the ECU. 

If you have P0420 cat system efficiency error its not as simple as getting an anti fouler.  There is a good chance that the catalytic converter is partially blocked causing a slightly restricted exhaust that would be bad for the engine. 
I had this happen to me and lived with resetting the light for a few months until I was able to find a used down pipe. After the install of the new component I picked up lost power.

Its advisable  to buy a good low millage catalytic converter with health flex sections.
There's no cat here Dev :) And I thibk that's how the OP wants it
Title: Re: P0420
Post by: Dev on March 25, 2019, 16:56
Quote from: shnazzle on March 25, 2019, 16:04
Quote from: Dev on March 25, 2019, 15:59
Quote from: shnazzle on March 25, 2019, 15:29
Ah! Without any cat it all becomes a fair bit easier.

The reason that the post-cat adjusts fueling is to keep the cat happy and work efficiently. If there's no cat to keep happy then that makes the job a lot easier :)

Any M18x1.5 o2 sensor extender will do.

Alternatively wire in an o2 sensor simulator. Basically it returns an oscilating "perfect" signal from the cat to give a permanent thumbs up to the ecu

Not exactly.  All the post cat sensor does is report that the cat is working as intended. It will have no bearing on the fueling and if the CEL is tripped it will not place the car in limp mode.

The reason why the fouler trick works is because it distances the 02 sensor just enough to fool the ECU. 

If you have P0420 cat system efficiency error its not as simple as getting an anti fouler.  There is a good chance that the catalytic converter is partially blocked causing a slightly restricted exhaust that would be bad for the engine. 
I had this happen to me and lived with resetting the light for a few months until I was able to find a used down pipe. After the install of the new component I picked up lost power.

Its advisable  to buy a good low millage catalytic converter with health flex sections.
There's no cat here Dev :) And I thibk that's how the OP wants it

My mistake. In that case the fouler trick works well.