P0171-P0174 to P0420

Hello guys,

I'm new to tacoma i just bought my 2011 tacoma V6 4.0 2months ago then suddenly when I'm driving 180miles check engine light came on and the car engine shut down so i tried to start it again and it work but the power is not there anymore, So i went to nearest oreilly they said worst case scenario would be the catalytic so he wanted me to try the "lucas fuel system cleaner" and so i did but it didnt worked so i changed my spark plugs , air filter and MAF sensor and after 1k miles the check engine light came on with different code which is P0420 does anyone here have the same situation before? If so, how'd you fixed it? Is it catalytic or 02 sensors? I wanted to try to 02 sensor since some of the forum saying it's worth to try that first? Thank you in advance. BOTH pictures below was the first code diagnosed

 

p0171 and 174 are lean, and possibly fuel pump related.

p0420 means failed cat bank 1, o2 sensors don't fix it, forums will post it, but it is usually just a bandaid.

Which code is stored right now, are you having driveability issues still?

 

Right now it has p0420 code and it drives fine but back in few weeks ago the p0171-p0174 came on but i changed everything even maf sensor not the fuel pump nor fuel filter. So do you think it is the cat? Thank you

 

Old thread but I’m gonna bring it back up. I have the same question here if anyone can help

 

If you have p0171/174 you need to troubleshoot those before going after the p0420.

Aside from the codes are you having any driveability problems?

Aside from simple checks like vacuum leaks, exhaust leaks, or a dirty MAF lean codes can't really be diagnosed properly without a scan tool to read at a minimum fuel trims, O2, and MAF data as well as possibly a fuel pressure gauge.

 

Aside from the codes I'm getting a problem at startup. it struggles a bit and then gets going, also it is a little shaky between 800 and 1100 rpm. My uncle said the cat could possibly be the cause if its not a vacuum leak or may, but I checked the vacuum lines and just cleaned the MAF. I also just changed all the spark plugs.

 

Sounds like a vacuum leak to me, the easiest way to find it is to have someone smoke test the intake system when the engine is cold.
You can also use water as shown in the video below (also goes into detail on vacuum leaks).

A catalytic converter will not cause lean codes, if they stop functioning they will throw a p0420/430, if they clog you will usually notice a severe lack of power.
https://www.youtube.com/watch?v=cuod8-zFSQ4

 

the thing is im not getting a rough idle like its going up and down. its just my car is shaky.

 

Vacuum leaks affect every engine differently, I'm not saying that's definitely your problem but it would be a good first step to rule out when dealing with p0171/174 codes and a poor idle.