Howdy folks.
My father’s 02 LS430 with 200k miles got a check engine light. When he had it checked it said it was the rear left oxygen sensor. But for a while, the car felt down on power. I changed the MAF sensor and it helped a nit hut still it feels like the car is choking out past 3500 rpm or so.

Im wondering if the cats are clogged and that ruined the oxygen sensor.
Can i have the cats checked with a Temp reader? Whats cats doyou recommend. Most go fro 350 on rock auto. .

Thank you in advance.

 

Most likely the Y-pipe is cracked. If the CATs are clogged then you have a serious problem somewhere in the engine.
Do you have a specific code number?

Why would you change the MAF sensor when the error code pointed to the downstream O2 sensor?

 

Thanks. Maf I changed years ago and it did help a lot in terms of power. That’s why I changed it. Still I feel the car is weak in mid range and upper rpm.

Car is very quiet . But I do hear lots of suction noise when trying to accelerate. Almost like a vacuum leak from the back of the engine. What could that be?

 

A cracked Y-pipe sucks air into the exhaust which adds oxygen, which the downstream O2 sensor detects and thus throws a code, P0420 or P0430.
Because it is sucking in the exhaust sounds normal.

If you have a cracked vacuum hose in the engine bay, that will be what you hear when accelerating.

 

Thank you.
code p0161 came up.

 

P0161 is a heater failure in the downstream O2 sensor on Bank 2 (right side).
You will need to get the sensor replaced to get rid of that one.
That will not be causing the power loss, but a vacuum leak would cause it.

 

Thank you. I’ll address those issues.