[RESOLVED] Recurring P0140 Code

TheRock0720 · 03-05-2011, 08:19 AM

Hey Forum,

I've been getting this code, P0140 - Downstream HO2 Sensor Stays at Center, on and off for the past couple months.

Tuesday 3-1-2011:
I was about to go get my car inspected and the check engine light came on... So I had to cancel the appointment. I checked the code and it was P0140 (listed twice?). I drove around and back home, then went out later that day for a drive around the roads and then filled my gas tank. About a mile after filling up I was sitting at a red light and I noticed the CEL went out, so I continued onto the highway about about a mile down the highway the light came back on. The light stayed on from here.

Wednesday 3-2-2011:
CEL was still on (same code).

Thursday 3-3-2011:
CEL went out in the morning when I started my car and stayed off for the rest of the day.

Friday 3-4-2011:
CEL is still off, and has been off, for the whole day. I finally deleted the code, P0140, when I got home from work. Hasn't come back on yet..

Saturday 3-5-2011:
Unknown yet... :hyper:

I have heard that the P0140 (Downstream HO2 Sensor Stays at Center) doesn't necessarily mean that your Rear O2 Sensor is bad, but it seems to be more common that there could be a wiring/ground/short issue with the wiring between the Rear O2 Sensor and the PCM.

Don't like posting links to other forums, but this one has what I am referring to above. ^
P0140 O2 Sensor??

Also, as you know, I deleted the code last night, and I am going to get my car inspected today. Since I deleted the code, will they see that and fail me or?? I know my friends Honda passed, he deleted the code right before he pulled into the bay. I also have a Chevy Lumina that was throwing a code and I deleted the code before I went to inspection and it passed. So I know it depends on the manufacture, thats why I am not sure about Mitsubishi.

razrman8 · 03-05-2011, 08:57 AM

Well what you can do now is just a visual inspection, yourself, of underneath the car. Check the o2 sensors wiring and trace it back as far as you can to ensure that your wires are not messed up or damaged. That is what I would do

As far as erasing the code to get it inspected, they will not be able to see that it has been cleared. If it is not on during the inspection then you should be alright. I have done it before, my car throws a EGR Flow Malfunction code when it wants to. Clear it, inspect it, you're good.

TheRock0720 · 03-05-2011, 09:19 AM

Quote:

Originally Posted by razrman8

Well what you can do now is just a visual inspection, yourself, of underneath the car. Check the o2 sensors wiring and trace it back as far as you can to ensure that your wires are not messed up or damaged. That is what I would do

As far as erasing the code to get it inspected, they will not be able to see that it has been cleared. If it is not on during the inspection then you should be alright. I have done it before, my car throws a EGR Flow Malfunction code when it wants to. Clear it, inspect it, you're good.

Thank you, I will check one last time to make sure there isn't anything "out of place" and for the wires.

P.S.- Sweet looking car! I love your rims, what are they?

razrman8 · 03-05-2011, 09:28 AM

No problem. Thank you. They are Rx-8 wheels.

bullettdsm · 03-05-2011, 10:19 AM

As for erasing codes; you will probably come up with a NR (not ready) for that code you erased (unless you have driven it enough so that it could cycle). I'm hoping that you erased just that cel as opposed to choosing erasing all. If you erase all, you should have to wait for all processes to cycle (some cycle quicker than others based on their criteria)). That will give you a possibility that you may have more than one NR. In CT (for my 97) I was allowed two NR's (which was cool because I had two, lol). I'm not sure what their parameters are in N.H.

MB

TheRock0720 · 03-05-2011, 01:57 PM

Alright I did go for inspection, and it did fail because 5 out of the 8ish sensors weren't ready to be tested. So I drove on Highway, Side roads, main streets, etc etc for totaling about 115 miles (I also shut the car off a few times in that 115 miles). I hope it passes now (going to get it inspected one more time tonight).

Does anyone know what the OBD Cycle is for our 1999 Eclipses?

UPDATE- Car will not pass with Check Engine Light on, a durr, I have the same code P0140 showing up. Wasted 100 + miles of gas for nothing. Getting new O2 sensor installed Monday.

__________________________________________________ __________________________________________________ ___

Any suggestions on the brand I should go with for the Rear O2 Sensor?

Also, P0140 doesn't necessarily mean the O2 sensor is bad, there could be a short in the circuit, correct? So any common places that people have came across?

TheRock0720 · 03-11-2011, 11:25 AM

Alright my car failed again today. After replacing the rear O2 sensor and 175 miles of driving and key cycles, the code is still popping up...

Are there known shorts in the circuit with my car for the rear O2 sensor?

Doug99RS · 03-12-2011, 06:41 AM

What type of sensor did you install in there and have you verified that the light is coming back on for the exact same code or a new one related to the same sensor?

Your first post describing the on-off-on light issue is really simple to explain. You had two P0140 codes in there because one was pending and one was active. Meaning... you had a hard fault that caused the light to come on in the first place and the pending meant that the sensor was tested again and would likely fail on the following test as well.

If your area does plug-in testing then a hard fault code or even a pending fault code will cause a failure, the only way you'll get through inspection is with no codes and all or most of the readiness monitors set.

The drive cycles for the mitsus are a pita, you just have to drive them in normal people mode for 60-80 miles and not in tuner mode.

TheRock0720 · 03-12-2011, 07:26 AM

Quote:

Originally Posted by Doug99RS

What type of sensor did you install in there and have you verified that the light is coming back on for the exact same code or a new one related to the same sensor?

Your first post describing the on-off-on light issue is really simple to explain. You had two P0140 codes in there because one was pending and one was active. Meaning... you had a hard fault that caused the light to come on in the first place and the pending meant that the sensor was tested again and would likely fail on the following test as well.

If your area does plug-in testing then a hard fault code or even a pending fault code will cause a failure, the only way you'll get through inspection is with no codes and all or most of the readiness monitors set.

The drive cycles for the mitsus are a pita, you just have to drive them in normal people mode for 60-80 miles and not in tuner mode.

We tested the old O2 sensor, and it was stuck at .45 volts and would not move. So we replaced the O2 sensor with a brand new one, and checked it out on the graph and volts and it was moving and responding as it should.

After replacing the sensor with a new one, we drove it and then deleted the code with our code reader.

I drove the car for about 150 miles (probably 10 key cycles or more) and took it to the inspection station. They hooked it up and mostly all the sensors we're up and running but the code P0140 was there (which is the same code I have been getting).

I am setting up an appointment for Monday 3-14-11 to get my car checked out further by my mechanic.

Doug99RS · 03-12-2011, 07:46 AM

There's a variety of "Brand new" sensors and I was specifically wanting to know what brand and what style. Was it Mitsu direct plug in, Bosch plug-in or universal-you-wire-it-up?

TheRock0720 · 03-12-2011, 07:56 AM

Quote:

Originally Posted by Doug99RS

There's a variety of "Brand new" sensors and I was specifically wanting to know what brand and what style. Was it Mitsu direct plug in, Bosch plug-in or universal-you-wire-it-up?

I don't know exactly which one he put in. I believe it was after market, but thats about all I know..

Doug99RS · 03-12-2011, 08:04 AM

If it was a plug-n-play then your chances of it being acceptable are decent. If it was a universal that he had to wire in himself then your chances are low.

TheRock0720 · 03-12-2011, 08:40 AM

Quote:

Originally Posted by Doug99RS

If it was a plug-n-play then your chances of it being acceptable are decent. If it was a universal that he had to wire in himself then your chances are low.

It was a "plug-n-play", the testing and install took a total of about 45 mins or less.

bullettdsm · 03-12-2011, 06:11 PM

Did you check your cat and your exhaust? Could be a bad cat or an exhaust leak (before the cat). What your rear O2 is there for, is basically to check the cat. If you have an exhaust leak or a bad cat, the expected values of the rear O2 may not match and may throw a rear O2 sensor code.

MB

TheRock0720 · 03-13-2011, 07:02 AM

Quote:

Originally Posted by bullettdsm

Did you check your cat and your exhaust? Could be a bad cat or an exhaust leak (before the cat). What your rear O2 is there for, is basically to check the cat. If you have an exhaust leak or a bad cat, the expected values of the rear O2 may not match and may throw a rear O2 sensor code.

MB

Sorry I did forget to mention, I recently installed a new direct fit cat because I was getting a P0420 code. My exhaust is pretty solid, there was one minor leak, but we patched it up and doesn't seem to be an issue.

VelocitàPaola · 03-13-2011, 08:51 AM

Quote:

Originally Posted by TheRock0720

Sorry I did forget to mention, I recently installed a new direct fit cat because I was getting a P0420 code. My exhaust is pretty solid, there was one minor leak, but we patched it up and doesn't seem to be an issue.

Are you sure this new catalytic converter is actually a catalytic converter? A lot of "high flow" cats on eBay are actually just hollow tubes. Even actual high flow cats can trip a downstream O2 sensor code.

TheRock0720 · 03-13-2011, 09:33 AM

Quote:

Originally Posted by VelocitàPaola

Are you sure this new catalytic converter is actually a catalytic converter? A lot of "high flow" cats on eBay are actually just hollow tubes. Even actual high flow cats can trip a downstream O2 sensor code.

Advance Auto Parts: Catalytic Converter - ULTRA Direct Fit by Walker - Part 15848

That is the Cat that I bought and installed. ^^

Doug99RS · 03-13-2011, 11:38 AM

Is this code something new that has shown up since the cat replacement or was this code there as well as the p0420?

Did you have to heat anything like the cat bolts or oxygen sensor to replace the cat?

TheRock0720 · 03-13-2011, 12:03 PM

Quote:

Originally Posted by Doug99RS

Is this code something new that has shown up since the cat replacement or was this code there as well as the p0420?

Did you have to heat anything like the cat bolts or oxygen sensor to replace the cat?

The code P0140 was coming and going along with the P0420 code. So the P0140 code was present before the P0420.

And I didn't have to heat anything up to remove the old cat.

TheRock0720 · 03-15-2011, 03:15 AM

Any other suggestions, forum?

VelocitàPaola · 03-15-2011, 08:03 AM

Quote:

Originally Posted by TheRock0720

Any other suggestions, forum?

Please don't bump your threads. As a proven member, you should know better.

Shake_Zulla · 03-15-2011, 08:17 AM

Quote:

Originally Posted by TheRock0720

Any other suggestions, forum?

I hate emissions stuff and am no expert but have you tried running 93 octane? It might get you a more complete burn and be just enough to be able to reset your codes and keep it off untill you can get tested. Maybe new spark plugs too? Just trying to think outside the box here. The time I had a problem with my old Eclipse I asked the guys at the testing place if they could put the sniffer on my car and run it then they gave me the numbers and I had a better idea of what needed to be done to pass.

TheRock0720 · 03-15-2011, 01:04 PM

Funny thing, when I first got this Eclipse back at the end of October of 2010 I put some 93 gas along with some Lucas Fuel Treatment and thats when I seemed to first get the codes. But I usually run 87 because gas is 3.40 here...and thats plenty.

But my mechanic is trying to find out what the common issues are with these eclipses are with this P0140 code so he doesn't rack up a bill just testing everything. So thats why I was hoping you guys would have good information...

Shake_Zulla · 03-15-2011, 04:25 PM

Quote:

Originally Posted by TheRock0720

Funny thing, when I first got this Eclipse back at the end of October of 2010 I put some 93 gas along with some Lucas Fuel Treatment and thats when I seemed to first get the codes. But I usually run 87 because gas is 3.40 here...and thats plenty.

But my mechanic is trying to find out what the common issues are with these eclipses are with this P0140 code so he doesn't rack up a bill just testing everything. So thats why I was hoping you guys would have good information...

Do you remember if the Lucas was an alcohol based solvent cleaner and how many times did you put it in? The reason why I ask is a lot of treatments have alcohol based solvents in it (IE ethanol, methanol, isoproply alcohol) and will damage engine parts if used on every tank of gas. Now as far as what specifically it damages I'm not sure. I read somewhere that it burns too hot but I can't remember where so just a heads up.

By the way... The difference between $3.40 and $3.60 on a 17 gal tanks is $3.40 total... be good to your car and give it what it wants

Or do whatever you want I'm just jealous you can get 93 at the pump... lucky sob.

TheRock0720 · 03-16-2011, 03:22 AM

Quote:

Originally Posted by Shake_Zulla

Do you remember if the Lucas was an alcohol based solvent cleaner and how many times did you put it in? The reason why I ask is a lot of treatments have alcohol based solvents in it (IE ethanol, methanol, isoproply alcohol) and will damage engine parts if used on every tank of gas. Now as far as what specifically it damages I'm not sure. I read somewhere that it burns too hot but I can't remember where so just a heads up.

By the way... The difference between $3.40 and $3.60 on a 17 gal tanks is $3.40 total... be good to your car and give it what it wants

Or do whatever you want I'm just jealous you can get 93 at the pump... lucky sob.

Yes I do know about alcohol and its alcohol based, I do add "dry gas" to my tank as well to keep everything in check. I haven't done Lucas in a few months, I still have some left, so when I get down to a quarter of a tank I'll fill up at 93 and throw some of that Lucas in there and see how she does.

Doug99RS · 03-16-2011, 04:16 AM

Octane rating has nothing to do with being good or bad to your car or even the quality of the gasoline. The octane rating is an indication of the burn rate of the fuel. The higher the octane the slower the burn so on a stock, good running engine that the manufacturer has tuned for 87 octane, you're actually creating a less efficient burn buy upping the octane you put in.

The reason high performance engines such as turbo car or SVT/HO/ETC ETC engines require a slower burning fuel is because of the pressures inside the combustion chamber from either this forced induction or the high compression. As you increase pressure you increase your chance of setting off the fuel charge prematurely. This is why 87 octane will "Ping" on a turbo car, the fuel charge is igniting before the piston is at the top of the stroke working it's way back down. The ping is the piston ever so slightly being forced BACK the direction it just came causing the noise and damage to the engine.

The only time you should up the octane rating on an engine/PCM set-up originally designated for 87 is if you already hear that pinging. This is usually caused by carbon on the top of the piston being so hot it prematurely sets off the fuel charge. Now you've got an ignition source at the bottom of the combustion chamber and the spark plug at the top igniting the charge as well. This causes the pinging as well and again is bad.

Don't bump up your octane unless your computer is designed to handle it, the compression ratio has been increased or you're running forced induction. If you do so without those changes, you're creating more problems.

TheRock0720 · 03-17-2011, 04:32 PM

Thank you Doug for that information, I already knew about that and I am sticking with the 87

.

Just to give you an update, Sunday 3-13-2011 I deleted the code for the P0140 code. I drove the car for the rest of the week (until now, Thursday 3-17-2011) and I went to see if I'd pass, just for the fun of it. Well...all 8 sensors were ready to be tested and NO Check Engine Light codes!!! I passed and finally got my sticker after 6+ months of trying!

Thanks guys/gals for all your info!