Check Engine Light on 1992 Land Cruiser indicating Oxygen Sensor Issue (code 21); what now?

[arooni]

Hi folks:

Pretty much a noob, I've changed oil before.

Anyway with my 1992 Land Cruiser with 195K miles and really no other issues.

I was taking it on the highway recently even though I rarely take it on the highway and the check engine light came on. I did buy some gas that I think might have been somewhat suspect at a BP but I can't guarantee.

I googled around (landed on THIS FORUM in fact, hence my new registration) apparently it uses a OBD-1 system to indicate error codes and so I jumped E1 and TE1 to find out the error code is 21. From what I could find this indicates an Oxygen Sensor issue.

So my questions from here:

1) Does this error code mean that I *must* replace the oxygen sensor?
2) Any point in me trying to do this myself? Or is the difficulty level too high?
3) Should I *not* drive the car anywhere until I can get this fixed?
4) Any point in resetting the EFI fuse and seeing if it trips again?
5) Anything else to keep in mind?
6) If I do get replaced somewhere, what's a fair rate/cost? Is there any point in asking for a discount if I have debugged it this far, or buying the oxygen sensor myself and giving it to the mechanic to save on costs?
7) It looks like there are two sensors, one before and one after the catalytic converter. Do both need to be replaced? Or just one? How can one tell which one to replace?

 

[Marco Lau]

replacing O2 sensors is a 15 min. job with a wrench. This is pretty much easier than changing oil. good luck.

 

[arooni]

Some people said it's worth trying to clean the existing O2 sensors before buying a new one. Is this worth a try?

 

[Marco Lau]

No....get 2 new sensors, replace them and be done with and your rig will thank you! By the time you see a CEL, your sensors are probably toasted.

 

[arooni]

Awesome thanks for the confirmation Marco Lau!

The consensus here seems to be OEM or Denso is the right manufacturer to go with. I'm guessing Denso would be a bit cheaper?

PS: I am frugal but want to do the job right

 

[arooni]

Just wanted to make sure I'm getting the right part:

Denso 234-4150 and Denso 234-4151.

Another dumb question: how do I find out which one is which for the replacement?

And where can I find a guide/walk through on what to do, which tools I might need?

Thanks for empowering me!

 

[jonheld]

replacing O2 sensors is a 15 min. job with a wrench. This is pretty much easier than changing oil. good luck.

On what planet is this a 15 minute job? If you replaced your O2s 15 minutes ago, it will take 15 minutes to swap them again.
But if they're 27 years old, they may need to be persuaded.
You'll want all new hardware, studs, and lots of penetrating oil.

 

[Marco Lau]

On what planet is this a 15 minute job? If you replaced your O2s 15 minutes ago, it will take 15 minutes to swap them again.
But if they're 27 years old, they may need to be persuaded.
You'll want all new hardware, studs, and lots of penetrating oil.

I just did this a couple months ago. Took me 15 mins. 4 bolts and disconnect 2 wiring clips. reuse all my existing hardware. Now i cannot say if you live in a rust bell which you probably do....good luck

 

[Marco Lau]

Just wanted to make sure I'm getting the right part:

Denso 234-4150 and Denso 234-4151.

Another dumb question: how do I find out which one is which for the replacement?

And where can I find a guide/walk through on what to do, which tools I might need?

Thanks for empowering me!

BTW, i believe the part number is
Denso 234-4150 for upstream left and Denso 234-4051 for upstream right

 

[arooni]

Thanks for everyone's feedback.

Any advice on what to do if the bolts are stuck? I was thinking of trying to spray it with some wd-40 a few days before.

 

[arooni]

On what planet is this a 15 minute job? If you replaced your O2s 15 minutes ago, it will take 15 minutes to swap them again.
But if they're 27 years old, they may need to be persuaded.
You'll want all new hardware, studs, and lots of penetrating oil.

When you say all new hardware, studs ==> which specific parts are you talking about?

When you say penetrating oil ===> would wd-40 suffice?

 

[Willy beamin]

PB blaster would be better. WD-40 is meant to displace moisture. Check your connections too. Could be that simple sometimes

 

[arooni]

PB blaster would be better. WD-40 is meant to displace moisture. Check your connections too. Could be that simple sometimes

Cool; will pick some up. By check your connections you mean check the existing electrical connections on the existing O2 sensors? They can become unplugged?

 

[Willy beamin]

Anything is possible. Stuff gets loose after 21+ years

 

[arooni]

I appreciate your time.

I just shot a few photos to make sure I located the part to replace correctly.

On my 1992 land cruiser this was on the driver side; and seems to be on both pipes that I think are entering the catalytic converter. I want to make sure I located them correctly because I was thinking one would be before and one would be after the catalytic converter. I didn't expect both to be on the pipes before the converter.


A few things that concern me:

1) I see an *actual hole* in the area right before the oxygen sensor. I will confess I'm a car noob but could this be a reason the check engine light triggers and indicates oxygen sensor malfunction?

2) Could simply getting someone to weld this shut (although the pipe does look rusted), fix my issues?

3) The metal brackets/flanges that seem to attach to the exhaust pipe are heavily rusted, and some of the nuts that seem to be holding the oxygen sensor seem to be almost flaking away. Is this the kind of thing that I'd need to take to a body/muffler shop and get them to weld a new bracket to?

4) I did call one muffler shop and they said that because these parts can flake off you might need a whole new exhaust pipe which sounds expensive and terrible. I was hoping welding might be an option (this would be outside my area of competence).

Thanks very much in advance!

 

[rghouse]

Is the check engine light still on? Mine false codes all the time, resets in less than 10 miles.

If you have the parts and you feel confident changing the sensors do it and drive it for a week. Get a manual. Welcome btw

 

[arooni]

It's still

Is the check engine light still on? Mine false codes all the time, resets in less than 10 miles.

If you have the parts and you feel confident changing the sensors do it and drive it for a week. Get a manual. Welcome btw

It's still on yes. I haven't manually reset it. Would you recommend pulling the EFI fuse and seeing if it comes back on?

Never had a check engine light come on in the last 4 years of running the beast.

 

[rghouse]

No it’s a hard code if it stays on

 

[Masud]

There could be a recall on this check with Toyota

 

[jonheld]

It's still

It's still on yes. I haven't manually reset it. Would you recommend pulling the EFI fuse and seeing if it comes back on?

Never had a check engine light come on in the last 4 years of running the beast.

Pulling the 15amp EFI fuse should always be the first thing that you do. Let the ECU clear stored codes and relearn the sensors.
If the code returns, then you can address the issue.
1st generation EFI based on 1986 technology.