P0171 and P017n Was: What tools do I need? (P0420 Bank 1 catalytic inefficiency on a 15 year old dual-cat vehicle)

In alt.home.repair, on 21 Aug 2018 10:56:52 -0400, snipped-for-privacy@panix.com (Scott Dorsey) wrote:
You seem to know what I wish I knew. Pardon me for horning in on this thread.

So the sensors are easy enough to remove and insert to just swap them, instead of putting in new? Because they cost so much, about $125 (for Toyotas, a lot more for BMWs I supppose.) (Of course I have the same code on both banks so I guess I won't be swapping, but taking one out worried me.)

I have a P0171 (Bank 1 too lean) and the same thing for Bank 2 (P017?) They tend to point to bad oxygen sensors
2005 Solara Camry Conv. with 3.3L

I've looked repeatedly and diligently for vacuum leaks. I've sprayed starter fluid into every crack. I've checked every hose.
I've cleaned using the special cleaner and then replaced the "filter" in the air cleaner tube. I've checked the air cleaner and it's clean.
I think I once made the codes disappear for 2 or 3 hours** apparently after I sprayed Liquid Wrench on the upper 02 sensor behind the radiator, when I was planning to change the sensor, but I couldn't reproduce that by spraying again. Still, it makes me think there is a leak there, in the threads?, that won't be fixed by merely replacing the sensor.
**Usually the codes reappear 15 minutes after being cleared manually.
I don't know how to check injectors, but since it's both sides and the car runs evenly, maybe they aren't the problem?
The two symptoms are two lights** on the dashboard and the fact that it usually stumbles, hesitates, when starting from a dead start, unless I press the acc just right. **VSC and what I read followed from VSC, trac off.
From reading I did months ago, I'm thinking the upper 02 sensors are more likely the problem than the lower ones, and I should replace the one that is easy to reach.
Or I could diagnose it the way you suggest, but the scan tool I bought didn't work completely and I returned it. I could buy another.

So I could be ruining my cat converter?
I'm hoping it's not that bad because I get 31 mpg on the highway, 1 or 2 mpg higher than what Toyota claims for the highway for a 2005 Solara convertible with 3.3L engine.
It's quite a bit lower in the city and I'm figuring I waste a bunch of gas every time I leave a stop sign and it stumbles.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I had a similar code 420 on my car. Numerous places told me that meant replacing the cat.
One place said that before doing that... to check out whether there was something in the engine throwing lots fo garbage into the exhaust,in which case replacing the cat would just be a waste of money.
He looked and discovered a defective EGR. He replaced it, and the 420 codes went from happening 15 minutes after each reset to one every couple of days...
Presumably there's still some gunk in the cat which slowly still sets off the alarm, but it's gone from being terminal to having a cold...
--
_____________________________________________________
Knowledge may be power, but communications is the key
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

No, the sensors are a bloody pain in the neck to remove and insert. It is no fun at all. But it's a thing you may need to do if you have a problem like the original poster.

Might be, but as I said to the original poster, look at the actual measurements on the scanner as the engine runs and you will see what is actually going on. Your engine may actually be running too lean on one side... if this is the case then you will likely see bank 1 running too rich.

That's never a bad plan. But if you have a leaky or plugged injector it won't find it that way. You -will- find it by looking at the plots from the scanner.

Okay, first of all throw out the Liquid Wrench, get kroil or break-free or something a lot more agressive because you're going to need it. Secondly, ignore the codes and look at the plots and see what exactly is going on with the sensors. The codes get set when a value is out of range for a certain amount of time. The plots let you see what is out of range and when and by how much, and it lets you see if the two banks are tracking or not.

The plots will start to tell you. Also I'd measure pressure at the rail just to make sure.

The sensors -after- the cat only tell you that the cat is good or not, they do nothing else. The sensors -before- the cat are used by the ECU to adjust the fuel mixture. If they produce bad data, the fuel mixture will be wrong in the opposite way as the data.

If you can't see the sensor values, you can't really do real diagnosis.

Maybe, if the other bank is running rich. Running lean likely won't hurt the converter, running rich will.

I'd first worry about fuel pressure. If the pressure at the rail sags badly when you gun the engine in the driveway, fix that. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I posted this already, and experience tells me both this and the previous one will probably show up, but it's still strange that the first one hasn't showen up on my computer in about 3 hours.
In alt.home.repair, on 21 Aug 2018 10:56:52 -0400, snipped-for-privacy@panix.com (Scott Dorsey) wrote:
You seem to know what I wish I knew. Pardon me for horning in on this thread.

So the sensors are easy enough to remove and insert to just swap them, instead of putting in new? Because they cost so much, about $125 (for Toyotas, a lot more for BMWs I supppose.) (Of course I have the same code on both banks so I guess I won't be swapping, but taking one out worried me.)

I have a P0171 (Bank 1 too lean) and the same thing for Bank 2 (P017?) They tend to point to bad oxygen sensors
2005 Solara Camry Conv. with 3.3L

I've looked repeatedly and diligently for vacuum leaks. I've sprayed starter fluid into every crack. I've checked every hose.
I've cleaned using the special cleaner and then replaced the "filter" in the air cleaner tube. I've checked the air cleaner and it's clean.
I think I once made the codes disappear for 2 or 3 hours** apparently after I sprayed Liquid Wrench on the upper 02 sensor behind the radiator, when I was planning to change the sensor, but I couldn't reproduce that by spraying again. Still, it makes me think there is a leak there, in the threads?, that won't be fixed by merely replacing the sensor.
**Usually the codes reappear 15 minutes after being cleared manually.
I don't know how to check injectors, but since it's both sides and the car runs evenly, maybe they aren't the problem?
The two symptoms are two lights** on the dashboard and the fact that it usually stumbles, hesitates, when starting from a dead start, unless I press the acc just right. **VSC and what I read followed from VSC, trac off.
From reading I did months ago, I'm thinking the upper 02 sensors are more likely the problem than the lower ones, and I should replace the one that is easy to reach.
Or I could diagnose it the way you suggest, but the scan tool I bought didn't work completely and I returned it. I could buy another.

So I could be ruining my cat converter?
I'm hoping it's not that bad because I get 31 mpg on the highway, 1 or 2 mpg higher than what Toyota claims for the highway for a 2005 Solara convertible with 3.3L engine.
It's quite a bit lower in the city and I'm figuring I waste a bunch of gas every time I leave a stop sign and it stumbles.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

No they don't.

Definitely - particularly if it reads lean and therefore runs rich - which would happen if it WAS the sensors causing the problem. You need to know how to read the block learn values etc on your scanner.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tuesday, August 21, 2018 at 1:47:08 PM UTC-4, micky wrote:

You have to take one out even if you're going to replace it. Taking the second out usually isn't much harder, unless it's in a bad location where something else has to be removed, etc. But all that assumes you know what you're doing and have the right tools. An example of what can happen otherwise is that recent thread about buying a car that had one cross-threaded with the hole fouled up.
Because they cost so much, about $125 (for

I've bought major brand BMW ones for half that.
(Of course I have the same

Both lean doesn't point to bad oxygen sensors as the prime suspect. First it would be odd for both to fail at the same time. Lean is usually caused by an air leak, eg a crack in the plumbing from the MAF to the throttle body or a broken vacuum hose.

Did you carefully check all the intake plumbing from the MAF to the throttle body? They frequently use rubber components and also tap off from there for various vacuum hoses. BMW X5 for example has a 4" round 90 deg elbow that is corrugated. It cracks. That one uses several hose clamps to keep it all together and if a joint cracks open a bit, you have a leak.
I guess you could buy one of those disco smoke makers and adapt it. I never needed to do that, but have heard that's a way to make the smoke.

Air cleaner won't produce a lean code, AFAIK. Clogged filter would restrict the air flow, MAF would know it and adjust the fuel accordingly.

I doubt that too.

I wouldn't think running lean would ruin the cat.

Well, it is running lean.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
In alt.home.repair, on Tue, 21 Aug 2018 14:57:21 -0700, Bob F

Hey, I'll try it. Can't hurt!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Oh, another thought on this old thread..... something that should always be checked if it's not your car: if you're seeing O2 sensor readings that are super-rich, especially if they are consistently rich on all sensors, make sure the engine grounds are good. Missing engine ground cables and/or severe rust can cause sensors to wind up with a poor ground reference and then you get bad sensor values.
The original poster's engine didn't sound like that sort of issue but it's a good idea to spend a minute doing a visual check of grounds no matter what you're looking at. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sunday, October 7, 2018 at 12:04:40 PM UTC-4, Scott Dorsey wrote:

Not a bad idea to check grounds, and it could contribute to problems, but hard to see how it would affect an O2 sensor, since it has it's own ground wire in the cable connected to it that goes back to the engine computer. They are not relying on the chassis or engine for a ground path.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 7 Oct 2018 12:04:35 -0400, snipped-for-privacy@panix.com (Scott Dorsey) wrote:

Sincethe almost universal implementation of either 2 wire or heated 4 wire O2 sensors the grounds are very unlikely to cause a false rich reading, and the grounds are likely to cause several other problems .
That said - checking grounds IS the first step in solving a vast number of electrical and electronic gremlins.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.