RAV4- replaced o2 sensor,charcoal canister and now needs AF sensor?

My 2008 Toyota RAV4 recently hit the 100,000 mi mark and all of a sudden we are up to our ears in needed repairs! Recently our check engine light came on and we took it to our local mechanic who said it needed an o2 sensor, which they replaced with an aftermarket part. 2 days later the light came on again. My mechanic suggested taking it to the dealership, who said that the o2 sensor was bad and put in a new one (my mechanic credited us!) and then also said that we needed a charcoal canister. We debated and decided to get the work done. Then 2 days later the light came on again. Now the dealership is saying we need an AF sensor (plus a long list of other unrelated things). MY QUESTION- could there be something else wrong in the system that is affecting all of these emissions parts? Are we putting out fires when the source is really something else?

Yes. It takes an experienced mechanic to save you money when the check engine light comes on. The codes generated by the CEL can point the finger in many directions and that’s where experience comes into play. Find a good independent mechanic that’s experienced and save yourself some money.

Did The Dealer Check For Any Bulletins Pertaining To Re-flashing (Revising) The Engine Computer? I See A Number Of Bulletins For These RAV4s.

It’s possible for a vehicle to post phantom trouble codes and illuminate “Check Engine” when a computer update is needed.
However, without knowing the DTCs (codes) they found I can’t be much help beyond that.

Do you have DTCs (like P0456, etcetera) listed on a repair order? Can you tell us what they are?


Without the codes that were stored in the cars computer, we would have no way of telling.

Look at your paperwork to see if they listed what codes were stored. Without the codes, we would just be listing every part that could trip a code.


There have been numerous bulletins for Toyotas of this vintage, concerning oxygen sensors, air/fuel sensors, and the canister

Some of them involve replacing parts. I’d be more comfortable installing exactly the parts listed in the bulletin, versus an aftermarket part, which may duplicate the superseded part

Some of the bulletins involve reflashing the PCM with updated software, as mentioned

Please post the exact fault codes you have/had, and we’ll try to help you

One more thing, and this is important . . . which engine do you have?

It wouldn’t be the norm, but it wouldn’t be that unusual either to have to replace the o2 and MAF sensors and the charcoal canister at 100k. It sounds like there is some kind of air/fuel mixture or evap system problem that is just starting up and being noticed by the computer.

Ask the shop if it would make sense to attempt to simply clean the MAF and canister, rather than replace them.

I’m wondering if there is some kind of contamination problem. Any change in gas stations? Was there any work done on this engine immediately prior to all this happening? Like replacing some gasket or another?