O2 sensor --> rough idle --> severe vibration??

[josephmartins]

This is a new one for me. Hoping someone can shed some light on the situation.

Replaced the two air-fuel sensors as well as the O2 sensor on a 2000 Avalon this past summer. Looks like that after-CAT O2 is acting up again. It threw a P0136 not more than two weeks ago. The car was otherwise running fine. Defective sensor maybe. I have a spare I plan to install tomorrow.

Anyway, two days ago on the way home--and after several miles of driving--the vehicle suddenly began shaking/vibrating pretty severely. At first I thought it had a flat or some other suspension issue. Everything checked out ok (except that the CEL was still on). I took the vehicle out for a test drive two more times over the past two days (allowing it to cool completely before each trip). Each time the behavior was the same. The first several minutes and miles of driving are fine. No vibration at all. But if I continue driving the vibration begins again and remains present no matter if I am driving 5 or 35mph.

When I stop, park the car and leave it idling the vibration goes away.

Could the faulty O2 be causing a rough idle that is, in turn, causing the vibration? Why no audible sign of rough idle while parked and no vibration at idle?

What other circumstances might cause a vibration to occur only after several miles of driving?

[csaxon]

If you have a CEL then get it checked. You may have a VVti problem.

[josephmartins]

Originally Posted by csaxon

If you have a CEL then get it checked. You may have a VVti problem.

Hi csaxon,

It seems the CEL is due to the P0136 bank 1 sensor 1 malfunction. Is there some other diagnostic to determine if there is also a VVti problem despite the lack of a trouble code?

[beantickler]

Is that the only code you show? Is there a rear o2 code pending or present?

[BiXLL]

Sounds like you could have a cat going bad. I had one that as it heated up it would choke off exhaust from expansion. Take note if your cat is getting extremly hot, mine even glowed red once!

[josephmartins]

Good morning beantickler and BiXLL

Yes P0136 is the current code.

BiXLL, funny you should mention a hot CAT. The Autozone person who read the codes specifically used the words "heated sensor". Perhaps that sensor is reading too hot (or has been destroyed by the heat) due to a failing CAT. I will look into that. Thanks!

[TedL]

Heated O2 sensors have been used for years. They have a built in heating element to let them give good readings sooner after a cold start. The heater circuit can fail.