Hi I'm Labeck from Tampa

I have a 2001 Tacoma With small 4 Cylinder.
It has 286000 miles
I have started getting a Check engine light and it only come on under 1900 RPM.
The code is 420.
I have attached some readings that caused the check engine light to come on.
see attachment....

 

Your truck is obviously high. Tell it to stop smoking and get a job.

 

Do you have an exhaust leak? Have you changed the A/F and O2 sensors? The only other thing in the FSM after those is the cat. If you have a CARB compliant vehicle, like mine, it can be an expensive fix.

I've had the code several times, but seemed to be caused by the other factors. not the cats. So check it out. I have a slightly used Denso A/F sensor (under 500 miles) if you don't mind used.

 

I have replaced the front and back O2 sensor and have cleaned the Throttle Body, which seem to help. I have cleaned the Map sensor.
I need to do a serious screening for a Vacuum leak. I also need to look for exhaust Leak.
Thanks for the help.

 

Check fuel cap for tightness. Seal may be cracked. That was source of vacuum leak on my 99

 

Did you look at the numbers of the long and short trim %'s I attached to my post?
I will check the cap. Thanks

 

Diagnostic for P0420 does not discuss long/short trim %:

Trouble Area

P0420

After engine and catalyst are warmed up, and while vehicle is driven within set vehicle and engine speed range, waveform of heated oxygen sensor (bank 1 sensor 2) alternates flatteringly between rich and lean (2 trip detection logic)

Gas leakage on exhaust system
A/F sensor (bank 1 sensor 1)
Heated oxygen sensor (bank 1 sensor 2)
Three–way catalytic converter


Since this is an exhaust side MIL, probably not the gas cap. But check anyway.

I've been chasing emission/evap error codes since I bought my truck in 2013. I'm good right now, but at no small expense.

 

also check your vsv they do go out and make the ecu think is a leak.

 

They sure do, but you'll get a evap code, not an exhaust code. VSVs can be hard parts to find also, but not impossible.