I have a 2011 ES 350 and it just went over 80k miles. After replacing the original battery, the CEL and traction light came on with error code P0138. A shop has changed the oxygen sensor with an after market and last time with a Lexus part. After each replacement, the CEL and traction lights return after ~50 miles.

The wiring has been checked a few times by different mechanics. Last time, they gave me the wiring diagram with trace route highlighted.

Could something be causing the oxygen sensors to go bad? Mass Air Flow sensor or Air Fuel ratio sensor? I really don't want to replace the ECM.

Any input would be appreciated.

 

Although my ES350 was 2011 and uses 87 gas, we changed the A/F ratio sensor and that fixed the issue of P0138. No more CEL!!!

See the below link for more guidance.
"This bulletin applies to 2007-2010 Lexus ES350 and RX350 models. Some vehicles may exhibit a MIL on DTC P0138 and/or P0158 (oxygen sensor circuit high voltage bank 1 or 2). In some instances, a P2195 or P2197 (A/F sensor signal stuck lean) DTC may also be present."

http://www.autoserviceprofessional.c...xus-a-f-and-o2

 

I'm having this exact same issue after replacing the battery. Got check engine light and VSC. Scanner pulled P0138 and P2195. The above link does not work anymore. cmanES350, sounds like you replaced the upstream A/F sensor only and that solved your problem.
What I don't get is how replacing the battery will make the O2 sensors go bad? Or was it just coincident? And in my case both the upstream and downstream sensors at the same time?

Can someone direct me to a service bulletin similar to the above? Thanks.

 

I just replaced my battery and got the MIL and VSC light on restart. She had sat for a few days due to dead battery and sputtered for a few minutes so let her run until she warmed up and on next start, all lights were off/normal. Never bothered checking codes |(unless it comes back. )

 

Thank you for the reply.

In my case, the car didn't have any engine or VSC light after the battery replacement. The car was stuck in the snow the next day and experienced some wheel spins and an extended period of VSC activation (maybe took a minute and some pushing to got it unstuck). A few km later, the check engine and VSC lights came on. And I'd read it somewhere that extended VSC activation also triggered the lights. Upon scanning for codes, I got P0138 and P2195.

The title of this thread suggested that, despite the codes, it was not the O2 sensors malfunctioning. Hopefully the OP or anyone can chime in to shed some light.

Thank you.

 

I have these exact same codes, came up while driving on the highway, please let me know if u found a solution. I replaced the oxygen sensor and it did not resolve the issue.

 

I reset the lights and only P2195 came back. Ended up replacing Bank 1 Sensor 1 and the light was gone for good.

I have a feeling that Toyota makes the VSC light come on along with the check engine light purposely. Many people (myself possibly depending on the fault code) would choose to ignore the check engine light, especially on an older car but when the VSC light is on and traction control is deactivated, people will get it fix.

 

Go to the dealer. Buy their battery. Have them install it

Fixed.

Or you can go to your guy some more and get charged for him to troubleshoot

 

tronimrich,
Are you suggesting that the check engine and VSC lights were triggered by an improper battery replacement? Can you tell me what they do at the dealer that is different than everyone else when it comes to battery replacement? Thanks.

 

I apologize for being sarcastic

I just feel that if issues only popped up once you replaced an OEM part, maybe you have the dealer install an OEM part and see what they have to say about the CEL and VSC

At least they'd be able to give an a look