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bikerlbf406
05-25-2009, 06:12 PM
My check engline light just recently came on. I had it checked at autozone & its coming up with code PO153, which is coming up w/ possible causes of oxygen sensor, fuel system running too rich or lean, engine misfire, or fuel pressure high or low. About a month ago, my check engine light came on for the very same code right after getting gas, and in a couple of days it went off by itself. Now it came back on & once again it was pretty much after getting gas again. This time the gas came from a different station. Any ideas what is like wrong & how to remedy this. The explorer still runs & drives great, so i doubt its engine misfire or anything like that.

Eric
05-25-2009, 08:13 PM
My check engline light just recently came on. I had it checked at autozone & its coming up with code PO153, which is coming up w/ possible causes of oxygen sensor, fuel system running too rich or lean, engine misfire, or fuel pressure high or low. About a month ago, my check engine light came on for the very same code right after getting gas, and in a couple of days it went off by itself. Now it came back on & once again it was pretty much after getting gas again. This time the gas came from a different station. Any ideas what is like wrong & how to remedy this. The explorer still runs & drives great, so i doubt its engine misfire or anything like that.

The fact that it (the light coming) appears to correlate with filling up suggests a problem with the evaporative emissions system. You may just need a new gas cap....

dom
05-26-2009, 01:00 AM
I concur. Sounds right.

DonTom
05-26-2009, 03:50 AM
My check engline light just recently came on. I had it checked at autozone & its coming up with code PO153, which is coming up w/ possible causes of oxygen sensor, fuel system running too rich or lean, engine misfire, or fuel pressure high or low. About a month ago, my check engine light came on for the very same code right after getting gas, and in a couple of days it went off by itself. Now it came back on & once again it was pretty much after getting gas again. This time the gas came from a different station. Any ideas what is like wrong & how to remedy this. The explorer still runs & drives great, so i doubt its engine misfire or anything like that.


See here. (http://www.obd-codes.com/p0153)


-Don- SF, CA

DonTom
05-26-2009, 03:52 AM
I concur. Sounds right.

I don't concur!

OBD2 code P0153 has nothing to do with gas caps.


-Don- SSF, CA

dom
05-26-2009, 01:21 PM
I tried looking up the code in all data, but lost patients. My reasoning behind agreeing with the gas cap being the culprit is the fact that this occurs at gas refill intervals.

Additionally, I've seen a lot of times just because a code comes from a certain sensor reading out of range variables does not necessarily mean that sensor is the problem.

It's just reading the results caused by the problem.

I'm not saying it's not the problem though. It very well could be the O2.

bikerlbf406
05-26-2009, 05:52 PM
Well once again the light went off on its own. Just like last time it went off right about the time I get down to 3/4 of a tank. I wonder if its the gas cap or not, cuz if the cap was bad, wouldn't it stay on?

DonTom
05-26-2009, 07:21 PM
Well once again the light went off on its own. Just like last time it went off right about the time I get down to 3/4 of a tank. I wonder if its the gas cap or not, cuz if the cap was bad, wouldn't it stay on?

If it were the gas cap, you would get a different code than P0153. See here for OBD2 gas cap code which is P0442 (http://www.obd-codes.com/p0442), NEVER PO153.

OBD2 systems don't get confused. Say after me, "It's NOT the gas cap and it has nothing to do with the gas cap!"

There can be countless reasons why the MIL goes off and on. Most likely it has to do with how many times you restart the engine. Different OBD2 codes have different criteria for turning off and on the MIL light and often has NOTHING to do with when the problem really comes and goes. For an example, some codes are not set until the car is started three times with the same problem each time. And will clear if there's ten starts without the problem (or whatever number). This is why the factory service manuals are needed these days. They will tell the exact conditions required for the MIL code to come and clear.

For an example, when I had my Ford problem with secondary air injection, it took two starts (after code is cleared by me) in a row with the air pump not working to get an MIL indication. Often a one time problem is ignored and won't set a MIL (Malfunction Indicator Light or "check engine light"). It seemed to me, at first, it only happened after a drive to Reno downtown and after two miles on the way back. But the truth was, I would clear the code at my Reno home, drive to downtown Reno (no MIL) and then on the way home I would get the check engine light. It had nothing to do with the distance, it had to do with driving two miles after the second restart of the engine after the code was cleared. But it seemed the code came on at the same place on the way home from downtown Reno each time, which really had nothing to do with it.

As I have said many times here, do NOT guess an OBD2 code. It's telling you what's wrong. Believe it. It is not making a mistake. It is NOT the gas cap, but it might have something to do with how many restarts or the distance to the gas station after starting and countless other such things that can add to the confusion until you read the factory service manual and see what conditions set the code. But regardless of the conditions for the MIL, the problem is related to what the code says it is, which is NOT the gas cap in your case.


-Don- SSF, CA

bikerlbf406
05-26-2009, 08:22 PM
With that being said, how do i go about setting to find which is the problem. Afterall the O2 sensor isn't the only thing that could cause me to get PO153.

DonTom
05-27-2009, 02:48 AM
With that being said, how do i go about setting to find which is the problem. Afterall the O2 sensor isn't the only thing that could cause me to get PO153.

That's right.

The best I can do for you is to look up the code in my 1997 Ford Mustang factory service manual and post the procedure (and the conditions required for you to get the MIL) in the next couple of days when I am back in Reno (where my 99 Mustang and books are).

I would bet on either a lose connection on one of the 02 sensors or one or more of the 02 sensors themselves if they have more than about 50,000 miles on them. If they are all old, I would replace all four.

Yeah, your vehicle might have four 02 sensors. Which engine do you have? If you have two catalytic converters, you most likely have an 02 sensor before and after each one.

For now, look for something obvious, such as an exhaust leak or a poor connection to an 02 sensor.

You have to get under the vehicle and check things.


-Don- SF, CA

bikerlbf406
05-27-2009, 04:19 AM
Thanks Don. I have the 4.0L V6 in it. As far as I know it only has once catalytic converter & has 2 O2 sensors. I'll have to see about getting underneath the vehicle & checking things out.

asemaster
05-27-2009, 05:05 PM
PO153 is a slow o2 sensor, bank 2 sensor 1. That's the front sensor on the driver's side. On a 12 year old truck I'd recommend changing both front sensors.

Bill

Eric
05-27-2009, 05:28 PM
PO153 is a slow o2 sensor, bank 2 sensor 1. That's the front sensor on the driver's side. On a 12 year old truck I'd recommend changing both front sensors.

Bill

Hi Bill,

Welcome to the site - and thanks for posting this reply. I think Tim'll be very appreciative!

DonTom
05-29-2009, 04:38 AM
Thanks Don. I have the 4.0L V6 in it. As far as I know it only has once catalytic converter & has 2 O2 sensors. I'll have to see about getting underneath the vehicle & checking things out.

Been having login problems. But I am at Reno now and here's how code P0153 sets a MIL.

1. The time since closed loop mode enabled is more than 100 seconds.

2. The average lean to rich response time, from 300 MV to more than 600 MV is over 125 ms.

3. The average rich to lean response time from 600MV to less than 300 MV is more than 125 MS.

4. The VCM ( Vehicle Control Module) turns on the MIL (check engine light) after the SECOND failure.

Conditions for clearing the MIL (besides clearing it all with your OBD2 code reader!)

Three consecutive drive trips without the problem. Code stays in memory without the MIL.

40 warm up cycles will clear the history of the error. A warm up is when the coolant raises 40F (22C) after a cold start.

Now that I have said all that, if you do not find anything obviously wrong, replace your O2 sensor. I would replace both, but it's the one on bank 2, sensor one (main sensor on the engine side of the CV) that's setting your PO153 code.


-Don- Reno, NV

Eric
05-29-2009, 05:49 PM
Hey Don - glad you're back in; I only just squeezed back in here myself!

DonTom
05-29-2009, 10:21 PM
Hey Don - glad you're back in; I only just squeezed back in here myself!

Yeah, but now I look like a FNG here! This is only my second message. Do you have any idea what went wrong?


-Don- Reno, NV

bikerlbf406
05-31-2009, 04:03 PM
Before I go replacing the O2 sensor I have one question. Wouldn't a bad sensor keep sending the the code to the computer, causing the MIL to stay lit? Seeing what Don said on the MIL light being set off, it just goes to show me that it is a fuel up causing the light to come on, as it will come on after 2-3 times of starting up after a fuel up. If it was a sensor bad, why is it only showing bad after a fuel up?

Eric
05-31-2009, 04:36 PM
Yeah, but now I look like a FNG here! This is only my second message. Do you have any idea what went wrong?


-Don- Reno, NV


Not a clue.

For 24 hours I could not even load the page. Dom thinks my ISP (or server) or Host (or whatever the "F" it is) was ID'ing me as a hacker and locking me out.

May be due to asshole spammers. We have been getting hit almost once a day lately and I have to ban/delete these bastards and their ?#@!$$$ posts for "Buy Viagra! Cheapest prices!"... does anyone ever pay attention to this crap? Why do they even bother?

I'd like to have them killed though, still. Just on general principles...

DonTom
05-31-2009, 10:42 PM
Before I go replacing the O2 sensor I have one question. Wouldn't a bad sensor keep sending the the code to the computer, causing the MIL to stay lit? Seeing what Don said on the MIL light being set off, it just goes to show me that it is a fuel up causing the light to come on, as it will come on after 2-3 times of starting up after a fuel up. If it was a sensor bad, why is it only showing bad after a fuel up?

More than likely, whatever is causing your code is an intermittent problem. Most likely, the O2 sensor is on the edge where it sometimes meets spec and sometimes does not. And your MIL will NOT show exactly when it does and doesn't, because certain conditions must be met to light up the MIL.

I don't buy that filling up the tank has anything to do with a P0153 code setting. Hasn't it ever gone on at other times? But as I showed in the previous message, there are many possible variables for setting the code as well as for it clearing.

I think it's just been a coincidence that it has been coming on after a fuel stop, assuming you read the code correctly! BTW, have you checked for new codes lately? Don't be surprised if you have more than one code in memory now and the other is related to your gas cap!

I would recheck for your codes and see if you still ONLY have P0153.


-Don- SSF, CA

bikerlbf406
06-01-2009, 01:44 AM
Yes I have rechecked the codes & the only code is the P0153. No the light has never came on, other then 2-3 starts after a fuel up. Thats the only time it come on. So if it isn't related to fuel ups it is one hell of a coincidence. I guess it is possible though that the O2 sensor is on the edge of going bad & therefore only showing bad at times. I'm just trying to make sure it isn't nothing else that could be causing it, as I don't have the $50 to pay for a new sensor, just to find out it don't take care of the problem.

DonTom
06-01-2009, 04:15 AM
Yes I have rechecked the codes & the only code is the P0153. No the light has never came on, other then 2-3 starts after a fuel up. Thats the only time it come on. So if it isn't related to fuel ups it is one hell of a coincidence. I guess it is possible though that the O2 sensor is on the edge of going bad & therefore only showing bad at times. I'm just trying to make sure it isn't nothing else that could be causing it, as I don't have the $50 to pay for a new sensor, just to find out it don't take care of the problem.

If there's no smog checks in your area, you might not even want to be concerned about your P0153. But you will get slightly better MPG when it works as it should, at least when driving at a steady speed.

Otherwise, you won't notice the difference. When you step on the gas, the car goes to open loop and then the O2 sensor is not even being used. The O2 sensor is important then cruising at a steady speed, such as on a level freeway. And then only your MPG will suffer. You will notice no other differences.

BTW, you can remove the O2 sensor and I bet you won't even notice any difference, other than a slight difference in MPG on the freeway.

IIRC, Eric drives one of his vehicles stuck in open loop.

If you're in a smog test area such as in this part of CA, you cannot have any codes in memory and you have to have enough miles on each sensor to "set". There's no reasonable way to cheat with OBD2.

IOW, if $50.00 is a big deal to you right now, and there's no smog checks in the area, just forget about the code P0153. It ain't going to hurt anything to be stuck in open loop. It will still be a lot more efficient than a carburetor!


-Don- SSF, CA

bikerlbf406
06-01-2009, 04:40 AM
Unfortunately we do have emission testing here in IL where I live, and thats exactly how they do it is checking the computer for codes. Meaning I'll have to make sure my computer is free of codes before going down for emissions. I guess since it really won't hurt anything, I'll just continue to drive it like it is, until such time I get the $50 & then replace it. Hopefully the state of IL will hold off on sending me the papers to take it down for testing until after I have a chance to repair it.

DonTom
06-01-2009, 09:45 PM
Unfortunately we do have emission testing here in IL where I live, and thats exactly how they do it is checking the computer for codes. Meaning I'll have to make sure my computer is free of codes before going down for emissions. I guess since it really won't hurt anything, I'll just continue to drive it like it is, until such time I get the $50 & then replace it. Hopefully the state of IL will hold off on sending me the papers to take it down for testing until after I have a chance to repair it.

You will have to put on about 100 miles or so AFTER you replace the O2 sensor before you go for a smog test. They can check something your code reader cannot. They can check if the codes are "set". "Set" means there's enough miles on the vehicle without the code coming on. IOW, you cannot cheat an OBD2 system by clearing the codes in memory just before the smog test. BTW, this is also true when changing the vehicle battery. If you change the battery just before a smog test, it will show codes "not set" and you flunk, even if there are no real problems. Always put on at least 100 miles with no codes or battery changes before going for a smog test.

If you can clear the codes and drive 100 miles with no code, you should be okay for a smog test. Just don't stop for gas. :)

Seriously, it's a real mystery why it (so far) happens only after a fill up. But I bet it has something to do with being the second time you start the engine after the first failure condition.

If it happens most of the time, try an experiment. Clear the MIL. Drive to the gas station as you usually do from the usual starting place. Stop the engine, but do not touch anything. Don't touch the gas cap or anything. Don't fill up. Wait a few minutes (the time it would take to get gas) and then re-start and see if you get the MIL.


-Don-

Eric
06-02-2009, 07:57 AM
Get a carb! Get a carb!

DonTom
06-03-2009, 12:51 AM
Get a carb! Get a carb!


"Get a carb! Get a carb!"

Even a broken EFI usually works better than a carb!

-Don-

Eric
06-03-2009, 08:20 AM
"Get a carb! Get a carb!"

Even a broken EFI usually works better than a carb!

-Don-


Not in my experience!

I'd argue the only thing a modern car really has over a pre-emissions/pre-computer car is the overdrive transmission. But it's easy to swap in an OD unit and then, presto, you have the highway legs and fuel economy of a current car without all the "safety" bullshit and overcomplicated electronics and emissions controls, which have turned cars into ridiculous money/hassle pits.

My '76 Trans-Am has an OD transmission and it trundles along at nearly 80 mph with the big 455 barely running 2,200 RPM - and that's with 3.90 rear gears! It gets not-bad mileage, is completely reliable, starts every time - and I can easily and cheaply fix anything that goes wrong with it.

"F" modern cars and all the crap they come with!

DonTom
06-05-2009, 02:26 AM
Not in my experience!

I'd argue the only thing a modern car really has over a pre-emissions/pre-computer car is the overdrive transmission.

Show me a carb that will give a perfect 14.7 air to fuel mixture at both sea level and at 8,000 feet in elevation and at 20 below as well as at 115F. If you cannot do that, your wasting gas, polluting the air and have an engine that won't last as long.

IMO, MPFI is one of the main reasons GM and others are doing so poorly. Their cars are lasting much longer because of the more efficient EFI system and the OBD2 that lets you know when things are not absolutely perfect well before you can get your first clue otherwise.


-Don- SSF, CA

bikerlbf406
06-08-2009, 05:06 PM
Well a few days ago I got gas, but not a full tank, and at a different station......and now after roughly atleast 5 starts later now, the check engine light came back on again. This time it is showing P0133 & P0153. Advance Auto Parts said that either both front oxygen sensors are bad, or the catalytic converter is going bad. So it looks like once I can come up with the money, I'll end up replacing both front sensors.

DonTom
06-08-2009, 09:32 PM
Well a few days ago I got gas, but not a full tank, and at a different station......and now after roughly atleast 5 starts later now, the check engine light came back on again. This time it is showing P0133 & P0153. Advance Auto Parts said that either both front oxygen sensors are bad, or the catalytic converter is going bad. So it looks like once I can come up with the money, I'll end up replacing both front sensors.

Yeah, they are both crapping out at about the same time, as one would expect. I suppose a clogged CV after the O2 sensor can screw up the readings on the 02 sensor. But if the o2 sensors are that old, they should be replaced anyway. And that's most likely a lot cheaper than replacing your CV. So I would replace the O2 sensors first and not feel too bad if it turns out to really be a CV problem.

BTW, I know some muffler shops will check your CV back pressure for no charge. I did that with an old VAN, and they didn't charge me a cent as they knew I would come back to them if I ever did have a real problem. BTW, the real problem in that van was a worn cam, something I never experienced before. And it was mainly an INTAKE lobe that was completely worn down, so that intake valve wouldn't move much. I would have noticed if I took the valve covers off, but never did. It had weird symptoms that I couldn't figure out, so I gave it to the experts to fix. A commercial shop near here had it figured out in about five minutes after I wasted many hours on it. Somehow their test equipment could find the problem without even removing the valve covers.

Well, at least by now, we should all be convinced that your check engine light problem has nothing to do with gas caps!


-Don- SSF, CA