My 08 loves to throw codes!

Greetings out there in 4runner land! My 08 sr5 v6 is 15 years old, I inherited it. It was my Stepfathers ,then it was my Mothers and now it lives with me at our house on Cape Cod. I look at it as an expensive truck because it cost me two of my favorite people in the world. Here's the good news; it just rolled 94,000 and runs like a bear. Very little rust despite being a mostly Northeast car. And everything but the TPMS (dead batteries) works,. I knew a vehicle of this age is going to develop issues and sure enough the O2 and A/F sensors started failing last year. I replaced both O2 sensors and one A/F sensor ( B1S1) and sure enough this year, just before the cars last emission related test EVER to be done to pass the CEL and related blinky lights lit up. OK, no big deal ; hook the old Snap-On Solus Pro and check the codes, This older unit does show live data, and I see that the A/F sensor that I did not replace (B2S1) due to the cost of the other parts to make the thing pass inspection the prior year had indeed failed too. I figured "well fine I knew it was only a matter of time so now its time" so off to Advance Auto, "Nope, don't have any and can not tell you when we can get you one." Next stop Auto Zone ( We Do not have O'Realys here) and they sold me a Denso looking box with an A/F sensor inside; it worked for two weeks and then I got the Christmas lights again .The code I got was A/F stuck lean B2S1 . AZ was kind enough to exchange the sensor for a new one as long as I still had the sales receipt, the original box, the failed sensor (not the original one, but the new one that failed) and I did have all of those things. So I got my last emission related inspection sticker and Thirty seven days after installing a new" Denso" A/F (B2S1) twice I got the Christmas tree dashboard again, plugged in the old Solus Pro and got " A/F stuck lean (B2S1)"Again.
Which brings me to my point. Have any of you had this problem?
Here are reasons for this that come to mind but I am all alone in my driveway scratching my head.
-1 Denso made a bad run of these things and they ended up a AZ.
-2 AZ bought a batch of bogus knock-offs labeled to look like the real thing.
-3 There is something else wrong with my fuel/ engine management system that eats A/F sensors early.
-4 I am a bone head and installed something incorrectly.

Sorry for for the long winded post, but if any one here has any insight, I am all ears.
Thank you

 

Now that you have the time since passing emissions, buy the real Denso sensors from RockAuto.com. Those are guaranteed to be real and the only place I buy mine.

Have you checked spark plugs yet? Make sure those are good, replace if unsure. Inspect coil packs for cracks when you do the plugs. Also, there's a good possibility the exhaust manifolds are leaking. Maybe time for new gaskets.

 

Yes I changed out the original plugs last year when I went through the sensors, and the coil- packs all test out fine on my Fluke 45. When this thing runs right it runs right. I really think I bought phony A/F sensors; hence their short lifespan. or may-haps there is something else that is killing them early. And despite the heat shields falling off of the cats The stainless exhaust is tight.

 

Thanks for the Rock auto Link,I had almost forgotten them. I did indeed buy yet another A/F sensor from them for about $100 less than "Auto Bone" ; replaced B1S1,cleared the code that was showing and enjoyed a normal looking panel for about three weeks. Then I got a Cel again, it was B2S2; I shrugged it off as an anomaly, cleared it and it came back a week later. I have forgotten what that code number was but the message was that the value Of B2S2 was Too far away from B1S2. So again read live data; and sure enough there is a disparity in the two downstream o2 sensors report to the the ECU and cleared all codes again. Now I am getting a CEL with a different code that is pointing toB2S1 (Replaced last year along with B1S2 and B2S2, from AZ) showing that it is "lazy" B2S1 too slow; I had no idea at the time that I should log all of this .
So, I have ordered one more AF sensor and two more Downstream o2 sensors from Rock Auto. I do NOT like to just Shotgun parts at a problem; but i do suspect that AZ has a large supply of "questionable" sensors that may or may not work for a while and then do not work. Or there is another issue with my 94000 mile engine that I am simply overlooking; I dont think its my low mile motor.

 

Hi there,
Did you ever get to the root of the issue? Im having similar issues with my 2011 with 2014k miles on it.

 

Mike-E-S Sorry to take so long but what I have concluded is that the sensors that I bought from A-Z failed very early. I don't know why. The sensors I bought from Rock Auto have held up just fine. No Issue since installing the last rock auto sensor.
Good Luck

 

I have same vehicle. Check the gas cap. I've had to replace mine 3x already. Always with OEM. Soon as they go bad, it throws one of those P codes and last time it threw a different code than the priors, but it turned out to be same bad gas cap problem.

Probably not your problem but at least make sure it's good.

 

That is a good bit of advice, and I did indeed get the same dash Lights (blinking TC and Decent control indicators along with a check engine light) when my gas cap failed. I did figure that one by reading here on this forum. Then I got my Solus -Pro and got different codes ;I think it was EVAP SYS related and the scanner pointed right at the problem , makes sense.

 

Well Now ,the same problem has returned. This thing is driving me nuts! Snap on Solus pro says banks 1&2 too lean. I have cleaned and replaced the MAF. Wich now fluctuates =/- 5.5 to 3.8 G/s After I cleaned it it would hang at 5+ G/s as original

 

284k miles….I buy so many parts at my Toyota dealership that when they see me they give me 25-30% off on factory parts. When it comes to sensors or electrical item I go to the dealership. My 1999 Tacoma has 263k. When chasing sensor issues sometimes it pays to pay a little more to get the desired results.

 

If you clean the caps O ring and put silicone grease on it the problem is fixed no need to keep replacing caps.

 

Denso is OEM. Buy Denso from Rockauto and save $$ over the dealer. My 4runner is over 348,600 miles and I run Denso for the electronics and sensors.

 

Going back to the the source of of my original p- code which was " fixed " with a genuine Toyota gas cap , for a while ;the grease seems like a good idea . so I'm going to try that despite the lack of any evap code (also absent during the second event; but not the first event). I do think these downstream o2 codes are indeed erroneous and caused by some other issue.
Sometimes I will start the thing up and it will not have a light-show going on. Then I will pull a 16x8 landscape trailer for a day and the thing comes back . Sometimes I clear the codes and they stay gone for a day or two; and then the thing runs like shit for second and the lights are back , it always feels like the engine is misfiling or the transmission is in too high a gear and the engine is "lugging", and then I am yelling at the dashboard again. I have this gut feeling that this is a VVT issue,and that is never good. No VVT codes though..............

 

Just remember those codes are mostly nothing unless you’re really having a problem and to try forcing you to run to your stealer dealer service dept.

 

There is a drive-ability issue here that is bothering me. I think that this should be fixable , if not I will just tear the cluster out of the dash and castrate all of the dum-dum lights and let it eat. If I am going to need an engine I,m going to need an engine . I don't like that; but I am not scared. I have changed out Detroit 671 cylinder heads in parking lots on Islands, miles away from my tool box; I should be able to hack this. Even at age 58 (cringe).

 

I do hope you get fixed as best as can be fixed. I am just pointing out what many times these codes really are.

 

I concur with you about how OBD 2 can send a tech down the wrong path if they believe everything the scan tool reports as factual. The real world keeps being the real world and does keep proving old tech (devised in the 1990s) questionable as to where it points.

 

Me too. On my 3rd gas cap, 2008 197k miles. Autozone cap did not work, need OEM cap.

 

Lots of good advice here.
I will share my OR auto store electric part saga.
My original Idle Air Control Valve on my 220,000 mile 2004 pilot showed up on OBD2 check engine which explained the pilots no idle.
I removed throtle body to access the IAC that mounts under it. Sure enough, choked with carbon. Tested with 9vdc battery-it did not click so valve was stuck.
I naively bought a good brand (forgot brand) from OR.
Put everyting back together. It ran 2days then no idle again, same CEL code.
Okay pulled everything apart again, exchanged IAC for another one supposidly from warehouse. I checked it with 9v battety and it clicked. I installed it and it also quickly failed. Hmmm now I am sure something is wrong. Are the returned parts being resold or sent back to distributor?
I spent couple hours cleaning the original Honda IAC -tested it -it clicked! Reinstalled it and it ran fine till I rehomed the Pilot a couple years later. Probably still working.
I will be very careful on my sourcing components from now on!
Lesson learned!

 

Sorry you live in a state where those tests are required, if it's the fuel "gas" cap just clean the O" Ring with denatured Alcohol and apply grease there is no need to buy a new cap.

As for these random check engine lights if your 4runner is starting and running good and gas milage has not dropped, what do is clear the codes and keep on a trucking many who go to Auto Zone for codes get sold about everything Auto Zone can sell them and most times it's not the or needed or correct part that is really needed.

Same gos for the Toyota Dealer Stealer non service Dept.s i was even told when i first bought my SR5 08 4runner by a Toyota service Tech. that they were on commision he even told me this, a really good warning and reason to stay far away from their non service Dept. not once have i ever returned to those dealer stealer bums.

 

Update: So all was ok good for about a year, until it all started again. I have not hired out a job on any of my vehicles for almost forty years, except for tires and glass. Again, got out the Snap-on Solus pro and was getting the same codes and blinky lights as before. At that point, I figured I was going to have to take the thing to a shop, and managed to talk the owner into just doing the diagnostic work, and if it was not too spendy; the repair. He actually did listen to the whole saga, including my thoughts about counterfeit or incorrect parts sold by the local parts stores. And he called me back later and said he could fix it if we replace all four (2xA/F and 2x O2) sensors, and said the parts from Toyota would cost $700 or so dollars plus labor to install.
I was in utter disbelief. At first, I argued that I had just gone through all of that stuff a year earlier. I listened to him as he explained that they had used three different scan tools and back probed the connectors on all four of the sensors on both sides and said he found one A/F' "open circuit" the other one intermittent and the O2's downstream all over the place, and recommended we change them all with genuine Toyoya parts. I simply could not argue with the sound logic of his diagnostics. I paid the man for his time and called the local dealer's parts dept. $560 for parts later, I installed just the two A/F sensors because at this point, I was thinking the incorrect O/2 readings were caused by the incorrect fuel trims being determined by the faulty A/F sensors. And I was right. Now the 08 4runner runs perfectly, no codes, no intermittent lumpy idle, no "lugging", no blinky lights. So, for now, I am happy. Without going into arguments or shit-storms about how I finally got my situation straightened out, I would like to share this somewhat informative video by an independent shop owner who works on Toyota and Lexus. Take it for what it is. https://youtu.be/gyZ7YGzP3h8?si=QR1pb5sKj-bjmmz2

 

Well i'm late to the thread, but i just replaced both forward bank O2 sensors with either Denso or Bosche sensors from RockAuto. I also bought the two rear O2 sensors as well but haven't replaced those yet... probably will during my next oil change. I think each sensor was around $50/ea, so roughly $200. The fronts are fairly easy to replace, just go through the wheel well. Just need to pull back the splash guards to gain access. Been a few months and it fixed my CEL and she now runs great. I think Denso makes the OEM Toyota sensors. Either way, sounds like you got it all sorted out but for anyways else that may come across this thread.

 

I feel these O2 Sensors will just keep failing becauce of the heat and pressues they have to deal with in the exhaust systems, so your going to have to keep replacing them.

 

H

Having replaced them (A/F sensors) four times in just over two years with parts labeled Denso in Denso boxes from three sources, I'm done with aftermarket sensors for that application. The Man in the link I posted will explain it, I believe his years of experience speak volumes. He describes the differences between OEM and aftermarket very clearly.. It's just not worth it not to use OEM there. The downstream sensors (O2) that I bought from Rock Auto seem to be fine, but I'm just a guy with a Box full of tools and have never done much work on Toyotas.