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What do you think the solution is?

  • Replace Bank 2 Sensor 1 Sensor

    Votes: 5 100.0%
  • Fix unknown, thus far, Exhaust Leak

    Votes: 0 0.0%
  • Replace Bad Catalytic Converter

    Votes: 0 0.0%
  • Place a charge of C4 inside the vehicle and energize

    Votes: 0 0.0%

  • Total voters
    5
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Discussion Starter #1 (Edited)
2007 FJ Help (P0158 - Bank 2 Sensor 2 - High Voltage) Code

Dear Forum-

I have searched, and found information, but was wanting some additional opinions.

Just purchased a 2007 and it has kept giving me a "Bank 2 Sensor 2 - High Voltage" code. I viewed the live data on my scan tool, and the voltage was holding at around 0.8+ on voltage... where the Bank 1 Sensor 2 voltage was varying, but never went higher than .75.

So I found out this was a post cat, driver's side, O2 Sensor error. I purchased a Denso replacement and after watching the live Data on my scan tool... I got the same error and values.

So then, to eliminate the possibility I got a bad replacement sensor... I swapped the Bank 1 Sensor 2, and Bank 2 Sensor 2, sensors...

Still get the same error and live data values.

So I have come to the conclusion that the problem is not with Bank 2 Sensor 2 and must be some issue further up towards the engine.

Both Bank 1 Sensor 1, and Bank 2 Sensor 1, have extremely similar values on the live data... so I was thinking that should indicate they are not defective and causing a problem downstream?

The Cat Temps on the two front are identical... and the cat temps on the rear are matching as well... and I don't get a low cat efficiency code or anything, which is why I would be confused if it's indeed a bad cat.

I have seen posts where some people replaced the Bank 2 Sensor 1, and it fixed it.
I have seen posts where people have found an exhaust leak causing the problem.
and I have seen posts where it could be an indication of a bad catalytic converter.

Anyone have any other tests I can do myself, to try and narrow this problem down? I know if I take it to Toyota they will probably recommend replacing all 4 Oxygen Sensors, all the Cats, and of course the muffler bearings too, to the tune of several thousands of dollars.

I'd greatly appreciate any advice and have a great week!

-Jim
 

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The output voltage of the post-cat oxygen sensors decreases as the oxygen content increases, and increases when the O2 level is low.

You didn't specify the actual OBD-II code you recorded, but it sounds like it may be P0158. The higher-than-normal voltage output may indicate a rich mixture on Bank 2. This can be caused by a leaky fuel injector, but there may be other contributing factors as well. How many miles are on the engine, and does the engine burn ANY oil at all?

Have the air/fuel sensors (Sensors #1 on both banks) ever been replaced? If you have over 85-100K on the engine, they are due for replacement, even if the output of both the Bank-1 and Bank-2 A/F sensors is "similar", voltage-wise..

Were there any other pending codes stored in the ECU?

After clearing the code, how quickly does it reappear, and under what driving conditions?

The first thing to do is to clean the mass airflow sensor in the intake tract, just to make sure that it is not contributing to a bias in the system. Then, run a few bottles of fuel injection system cleaner through the system.

Find a long, steep grade, and climb it several times at maximum legal speed, putting the engine under the greatest load you can and getting the cats as hot as you can.

If the A/F sensors have more than 85-100K miles on them, replace them both, using ONLY OEM Denso parts.

If the code persists, you might consider a professional injector cleaning. More laborious is swapping the injectors between Bank 1 and Bank 2, and seeing if the failure follows the set of injectors.

Do you burn only Top Tier gasoline?
 

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Discussion Starter #3 (Edited)
Thank you so much for the reply.

Yes it is a P0158, sorry I left that out. The engine has 126k and although I have only put about 1200 on it... I have seen no oil burn off yet.

I will clean the MAF and I've been running some Lucas fuel treatment, I have run about 6 tanks so far and have used both 87 and 93 octane from good stations evenly.

There weren't any other codes and after clearing... during say a 10 minute drive cycle of city/highway mix... it will store a "pending code 0158"... then the next drive cycle is when I get the light and related 0158 code.

So could I just start with the Bank 2 Sensor 1... first.. since that is the side erroring? It would save me a bit of money until Bank 1 needs it!

Thanks for the advice and feel free to and more!

-Jim

Also, the previous owner installed a TRD air filter, so I am going to service that, and not over oil it.
 

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Ahhh ... if you have an oiled-element air filter, by all means clean the MAF first. There is a long history of oiled air filter elements contaminating the MAF.

Also, you mentioned that you purchase gasoline from "good stations", whatever that means.

You didn't mention if these stations offer only Top Tier rated gasoline, with improved anti-deposit detergency.
 

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Discussion Starter #5
Sorry, I should have been more detailed on the gas stations...

What I meant was I don't buy gas from places like "Joe Bob's Filling Station and Rib Joint"... but I do go to Shell, BP, Marathon near the interstate, so I'm guessing their fuel is good quality, but also pretty fresh.

I cleaned the MAF and Throttle Body today with the appropriate CRC branded cleaners. Both looked much cleaner afterwards.

Cleared all the codes out and went for a drive, tried to load the engine and observed cat temps at peak, front around 1520, and rears about 1350 degrees. Still showing Bank 2 Sensor 2 voltage around .850, while Bank 1 Sensor 2 hangs around .6 give or take, but not higher than .75.

Still throwing the P0158, so I've ordered a replacement Denso sensor for Bank 2 Sensor 1 location. That is still the only code. Comes on within 5 minutes of driving... as I can clear the "pending code" on the move... and it will return in a few minutes.

If the new A/F sensor doesn't fix the problem, I suppose I'll just take it in to Toyota and maybe their computer can detect a leaky injector or some other issue.

I suppose I could try some of the "through rail" type injector cleaning systems... but I'm guessing I could get it diagnosed for not much more than the cost of all that DIY guesswork.

Thanks for all the help and I'll gladly take additional if you or anyone else has more to give.

-Jim
 

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You might check to see if the fuel sold at the gas stations you frequent meets the detergency requirements to qualify as Top Tier.

From the Top Tier website (http://www.toptiergas.com/):

"TOP TIER™ Detergent Gasoline is the premier standard for gasoline performance. Eight of the world's top automakers, BMW, General Motors, Fiat Chrysler Automobiles, Honda, Toyota, Volkswagen, Mercedes-Benz and Audi recognize that the current EPA minimum detergent requirements do not go far enough to ensure optimal engine performance."

"Since the minimum additive performance standards were first established by the EPA in 1995, most gasoline marketers have actually reduced the concentration level of detergent additive in their gasoline by up to 50%. As a result, the ability of a vehicle to maintain stringent Tier 2 emission standards has been hampered, leading to engine deposits that can have a big impact on in-use emissions and driver satisfaction."

The list of gasoline retailers whose products qualify for the Top Tier rating can be found here:

Retailers
 

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Discussion Starter #8
FJTest-

Thanks for the information on gasoline stations and regulations, I'll definitely check into that. My opinion on fuel quality went down drastically when I began having a ton of trouble with ethanol in my small engine stuff... so who knows what kind of junk fuel we are getting these days.

GearWrench-

In reference to the Bank 2 Sensor 2... on my scantool, looking at live data driving around, it does vary... but usually does not go into the .7xx's, mostly just stays at .80 or greater.

I just got back from Walmart, I'm going to give a full bottle of Seafoam in the gas a try... just to see if it will improve that possible leaky injector. I'll give it a full tank, and then go to the next option if no improvement.

Thanks for the information and interest in helping me!

-Jim
 

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Please let me know what you did to fix this problem. I have the exact same problem you are having right now. I've replaced Sensor 2 on both bunk 1 and 2, replaced spark plugs, and gas cap but still getting the same code.

I have also tried the URD Rear sensor simulator but still coming up with the P0158 Bunk 2 Sensor 2 high voltage code.
 

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Discussion Starter #10 (Edited)
Ramon-

I definitely will update the thread once I get it fixed, no worries.

I just got in the new Bank 2 Sensor 1, Air Fuel Sensor, so that is my next replacement part.

It sounds like you haven't changed that part yet either, so hopefully after I change mine, it will fix it!

Also, I believe that with that URD Simulator, you have to have a valid Sensor 1 value, from the Air Fuel sensors, in order for it to work.... so maybe that might indicate that the problem is indeed Sensor 1. I sure hope so.

I'll update soon.

-Jim
 

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Discussion Starter #11 (Edited)
Thank you all for the help, I think I have it fixed for now anyway!

I got my new Denso Air Fuel O2 sensor from Amazon yesterday, about $102.95 shipped, for the Bank 2 Sensor 1 position... and while it was a bit of a pain to change... I think it worked!

My voltages were immediately lower, (leaner), and the exhaust even smelled less strong. Cleared out the existing codes again, and went for about a 15 minute drive... voltages on Bank 2 Sensor 2 were similar to Bank 1 Sensor 2, and no errors! Thank goodness.

It seemed to idle and run better, and surely my dismal fuel economy will improve. Maybe I can get the advertised 17 MPG, haha, as I was only getting about 14 on the highway.

Thanks again to everyone, yall have a great week.

Oh and Ramon, if you decide to replace your Bank 2 Sensor 1 A/F Sensor... I ended up having to use a short extension and a universal swivel joint extension in order to be able to get on the O2 sensor socket I used. It was definitely a challenge and getting the plug out was a pain too. I decided to go in from the top (hood) to remove the plug first. Then I went underneath and broke the sensor free from down below. I imagine taking the front tire off may make the job a bit easier... but I was lazy!

Laying underneath, I put the O2 Sensor Socket on the sensor, with the offset down towards the ground. This put the offset underneath the exhaust pipe, and then I was able to get a good angle with the universal extension and the short extension on my ratchet.

Putting it back in was just the reverse, add some anti-seize to the sensor and then tighten it down. I did the plug again from the top, as it was easier for me that way. I have long arms, so that may have helped.

Good luck and I'd say if you replace that Upstream sensor... you'll be fixed too.

-Jim
 

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That's awesome new bro!!! I will replace bank 2 sensor 1 this weekend. I hope it works out just like yours did cause I also made an appointment with Toyota next week haha but I guess I'll be able to cancel it. Thanks so much for the update.
 

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Re: 2007 FJ Help (P0158 - Bank 2 Sensor 2 - High Voltage) Code

Your problem probably arose because the FJ discovered you are a Duke fan. dUKe sucks.
 

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This might be a useless contribution to a highly technical thread but I find that using Premium gas with minimum ethanol content makes my vehicle run better and minimizes problems with the fuel system.

It may be the placebo effect but I don't think so. Spending an extra $4.00 on a tank of good gas seems to me to be a small price to pay to avoid the pain in the neck of diagnosing problems like this and paying to get them fixed.

Also I don't care what anybody says even the 2014's like I have sure seem to run better on high end premium than on budget regular.

I seem to get about 1 mpg better mileage so I figure even the cost closely evens out especially with fuel costs as low as they are right now (and they are expected to stay at roughly this level through 2020).

YMMV

BTW, damn CAFE standards. I had to get that in. Lousy government bureaucrats.
 

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Discussion Starter #18
That's great to hear Ramon, I know it's a relief to have it fixed!

Take care and thanks to everyone for the replies and info recently too.

-Jim
 

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Good to hear Ramon, let me know if you get it fixed!

This is the sensor:
Denso 234-9051 Air Fuel Ratio Sensor https://www.amazon.com/dp/B0018JUJ9O/ref=cm_sw_r_cp_apa_l8THxb5PFDNB9

I'm having a hard time figuring out which sensor goes where. The amazon link to the Denso sensor goes to which bank/sensor? What are the part numbers for each of the 4 sensors? Are there 4 different part numbers? Or are some the same?

Is this correct? bank2/sensor1 = driver's side before CAT, bank2/sensor2 = driver's side after CAT
 

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Yes.

Sensor 1, aka A/F sensor is before first cat.
Sensor 2, aka o2 sensor is after first cat, before 2nd cat.

Bank 1 is passenger side, bank 2 is driver side (for a LHD FJ, lol).
 
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