[stal023]

Also there are a lot of mechanics I know of that suggest when one of the sensors fails, the others are likely starting to get "slow and lazy" so many of these mechanics will change all three at the same time. I don't recall how many "drive cycles" must be completed without an error to clear the P0155 but some of the codes require multiple "drive cycles" to clear. Others will clear on one completion of the self diagnostic. (like the P0457, fuel evap leak, most often a loose gas cap).

I did the drive cycle and the code cleared on its own and then I drove at least 500 miles and these two codes were given. Could the sensor I just bought be crap? What is the other code about? And why is the fuel reading only 1 O2 sensor?

 

[stal023]

Oh duh, P0140 is another O2 sensor so that makes sense it is saying only 1 is working but then why is it saying it is a closed-loop?

 

[stal023]

140 is saying Bank 1, sensor 2 but I don't see this even indicated on an astro. I see Bank 1, Sensor 1 as upstream driver, Bank 2 sensor 1 as upstream passenger (what I already changed) and then the downstream as bank 2, sensor 2. What gives?

 

[stal023]

Leeann_93, thoughts?

 

[stal023]

I just called the auto parts store and I can return that O2 sensor I just put in, (NTK), they would need to order a new one. AC Delco is $119 for this and the rear. Do I clear the code and see what happens? Do I replace the upstream passenger and the rear? Do I fork over a ton more money and get the AC Delco? Trying to get out of town this weekend. Thanks everyone.

 

[Leeann_93]

A code that points to a sensor isn't saying that sensor is bad and replace it.

It's saying that something's happening that the sensor cannot overcome. So it could be a dirty air filter, a dirty or bad MAF, a bad coolant temp sender, - anything that affects the fuel/air ratio.

 

[stal023]

Where does one begin to troubleshoot it?

 

[dramey]

Where does one begin to troubleshoot it?

The factory repair manual. I bought mine on ebay or you can download a digital copy from AstroWill.

 

[dchan51360]

As I mentioned one sensor can cause a cascade of other items since all three are supposed to work together to control the whole emission system.

You also mentioned that the CEL light was still on but you saw that the sensor went to closed loop. Did the light eventually go out as well? If not, it's possible that the code has not truly cleared. The emission system/computer may started working properly (closed loop) but it didn't actually clear the error. Because I don't use your particular software I don't know how it handles error and if it keeps them "stored" until you actually clear them. There are some software packages that keep the old info so you can "track" what got done. Is it possible it's just telling you that in your history you had a P0155 and that now the new error is P0140.

Do you know if there are other codes stored that you might not be aware of.

Actual description of P0140 is

P0140 Technical Definition: ​​​Oxygen Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
P0140 Meaning: Downstream oxygen sensor is not working properly
Most common cause: ​Faulty downstream oxygen sensor or wiring​.

very specifically: The engine code P0140 is stored in memory when the Electronic Control Unit (ECU) senses poor to no activity in the oxygen sensor corresponding to engine bank #1 (the bank of cylinders where cylinder #1 is located). The sensor 2 tag indicates the post-catalytic converter O2 sensor.

Explained as Driver side sensor, may be tracking properly (opening and closing) but the computer is not seeing a change on the down stream sensor (after cat) and since you don't have a dual exhaust this will be the same sensor. (behind the cat) as would be used by the sensor on the passenger side as well.

Cause can be bad sensor, (behind cat) bad wiring, and a bunch of other things as well (maf, etc)

Like I mentioned earlier. Changing the bad sensor (preheater actually) you probably no longer have a "lazy sensor" over there. This may now expose all the other sensors so that the computer now sees them as slow or lazy and thus change the code.

Again, I personally would clear all the codes, and then try completing a full drive cycle. See what you come up with. Remember that the computer is "learning" and trying to adjust to what's in your vehicle along with your "driving habits" and environment. If you only changed one part of the system which affects all the other parts of the system and don't re-learn their relationship to each other, you may be getting false readings. I suspect more however that your new sensor is responding the way it is supposed to, and now relative to your nice new snappy sensor, all the other sensors seem very slow to the computer. Possibly that the computer is using old data stored from the old sensors.

 

[stal023]

Thanks for the advice everyone.

I cleared the codes, then I installed a new air filter and cleaned the MAF. I did NOT do a drive cycle and rather took off for my weekend trip and decided to keep an eye on it since my gas mileage was not dropping.

The check engine light did come back on but just threw a P0141 code which my understanding is the downstream O2 sensor that could be caused from: faulty O2 sensor, faulty wiring/connection, engine coolant sensor not working properly, or faulty PCM.

I always like to do the cheaper fixes first if I don't know what is going on. Since this error wasn't being thrown until AFTER replacing the upstream O2 sensor, it doesn't make sense to me that the wiring/connection is bad.

This could be completely unrelated but my coolant needs to be changed. Could this help this issue?

What is my next troubleshooting step?

Also, I just read this: "O2 sensor failures can be caused by various contaminants that enter the exhaust. These include silicates from internal engine coolant leaks (due to a leaky head gasket or a crack in a cylinder wall or combustion chamber) and phosphorus from excessive oil consumption (due to worn rings or valve guides). Replacing a fouled O2 sensor may temporarily solve the problem, but sooner or later the new sensor also will fail if the underlying problem that is allowing the contamination to occur is not corrected."

Should I be concerned about a larger issue?

 

[dchan51360]

how old are all the sensors? Were they all original? Again, O2 sensors do get "lazy" with age/use. When you changed the upstream sensor, the computer is now receiving faster and more accurate information. it uses this information and compares it with what is going on down stream. If the upstream sensor sends a reading to the computer, and the computer responds with an adjustment and sees that it was reflected in the upstream sensor, it will expect the same change at the down stream sensor. when you only change one lazy sensor for a fast sensor, the other lazy sensors will seem to the computer, like they are not reacting at the same speed as the new sensors and can cause your exact symptom.

Yes a lot of other things can affect this as well but I would change that downstream sensor and the other upstream sensor all at the same time, especially if you are pretty sure they are all original.

Part of the reason there is no "interval" for replacement of O2 sensors is they are expected to have a 100,000 to 150,000 mi life. Average life expectancy of 96 and later vehicles in the US was probably in the 75k mi range. (5-7 years). but as our vehicles are now often in the 150k-200k mi range and above, the O2 sensors are probably all starting to get "old and lazy"

The following is only one forum's suggestion so you can decide for your self.

https://www.counterman.com/technical-fo ... -replaced/

 

[Leeann_93]

This could be completely unrelated but my coolant needs to be changed. Could this help this issue?

Not in any way, shape or form.

Like dchan said, if you've replaced the upstream sensors but not the downstream sensor, there's a disconnect in the data that will throw a code.

 

[stal023]

how old are all the sensors? Were they all original?

Part of the reason there is no "interval" for replacement of O2 sensors is they are expected to have a 100,000 to 150,000 mi life. Average life expectancy of 96 and later vehicles in the US was probably in the 75k mi range. (5-7 years). but as our vehicles are now often in the 150k-200k mi range and above, the O2 sensors are probably all starting to get "old and lazy"

I suspect they are original although two of the sensors did not have the security pin in them. The upstream passenger did have the pin in. While this is an 04, I have roughly 120K miles on it.

I will order an O2 sensor for the rear. I want to order online since it is much cheaper than going to an auto parts store. I'd like to get AC Delco. (https://www.amazon.com/ACDelco-213-2830 ... olet+Astro)

Site says it fits my vehicle but will this work for the downstream? My understanding according to the auto parts store, the upstream and downstream are the same part number? How do I verify the correct part #?

 

[stal023]

Or this? https://www.amazon.com/ACDelco-213-2831 ... olet+Astro

 

[Leeann_93]

Downstream is the same as the passenger upstream. Driver's upstream has a connector that's the reverse of the passenger side.