Hi all

1996 Explorer 4.0L OHV engine...

Pulled codes P0153 and P1152, which both happened at the same time. Cleared them, but wanted more info from all you nice folks :-)

A couple of weeks ago, I was getting a P0420 too, but that hasn't come back. I got it once last year too, and cleared it, and didn't come back... Seems like I got it about the same time of year, when the weather starts getting colder out... but I'm a little more concerned with the other 2 codes, since they failed together today like that.

The engine has about 132K on it - and the previous engine used to leak AntiFreeze into the exhaust... but this was changed out more than a year ago... and it has been pretty good on not really throwing codes, maybe an evap code once in a while, (the gas cap code)

I just did Cat back exhaust, and no leaks (did this in the summertime)

So, should I buy a couple of upstream O2 sensors, and one or two of the downstream?

any other specific things to look for on this truck (the 96's) someone mentioned some other issues that may throw these codes, and I'd rather start easy/cheap first, before I spend $200 in O2 sensors, but I guess they only last 100K anyways?

is there anyway to test an o2 sensor? or can they fail intermintantly?

Also, are there the 2 up and just the one down? or 2 Down also? - Should I just replace them all? or not do that?

The engine seems to run fine, and don't know if it will come back, and when, etc...

If I'm gonna check for vaccum leaks, where are good places to look, specifically? -

Thanks to all!

 

1st let me say that O2 sensors are maintenance items, meaning that they require periodic replacement. Taking into account that your codes indicate both upstream/downstream of the CAT the probability of both sensors going bad simultaneously is remote.

I would be looking for an unmetered air supply, starting at the filter, MAF, air tube, intake manifold, vacuum lines, PCV, exhaust leak and wiring.. Fuel pressure.

 

not withstanding the 420 code - just the other two I got at the same time, which were the 0153 1152 codes, I thought these would be related?

Where is the PCV on this engine? in the valve cover? - are there any well known vacuum lines that are troublesome on these? - any easy way to check these for leaks?

I can throw a new air filter in, replace the PCV (if I can find it) and clean the maf sensor too I guess it has been over a year on that filter, so I'll change it anyways, like you said, PM is a good thing...

AN - do you have the same engine as this one? - 97 was the year they changed to the SOHC right? but if you have 360K on it, regardless - you must be doing something right :-)

 

We have 4 exploders in the family, my 97 being the lowest mlg, 92 has 467k, all original OHV.

The PCV is on the rocker cover, rear driver side. Make sure the cleaner you use on the MAF is residue free.

 

wow, so, mine having only 130K is just being broken in :-) - if I had a vacuum leak, wouldn't it have a rough idle too? - thanks

 

ok, so now it only threw the 0153 - guess this is the drivers side, Upsteam o2? - Aqua, since you have the same engine, and almost the same year (mines a 96 Sport) - how hard is it to get on that puppy and take it off? can I use a box wrench? - what size do I need? a 22mm? - also, where is the exact location of it? - I see a couple of things right at the end of the exhaust manifold, first looks like it is part of the evap system though, has a cloth braid around it - then there is something else about an inch down from that - is the o2 sensor past that, closer to the cat? - Can I do this in my Driveway, or do I need a lift to get at it?

thanks Aqua!

 

PO 0153 - To quote the Ford manual is a "HO2S Sensor Circuit Slow Response. See P0133 - The HEGO Monitor checks the HO2S Sensor frequency and amplitude. If during the testing the frequency and amplitude were to fall below the calibrated limit, the test will fail." That is what sets the code and a low system voltage might do that.

Ford lists the following areas to check: "Contaminated HO2S sensor; Exhaust leaks; Shorted / open wiring.; Improper fueling; MAF sensor; Deteriorating HO2S sensor and Inlet air leaks."

Know that this list was published based upon engineering and may or may not cover the reason the code was set. Experience is usually the best guide and you can find that some of that on this forum.

Based upon the statements of those who have some experience with these things, the failure of an HO2S sensor is NOT common but the MAP is a common concern.

So, based upon what I have experienced with my vehicles and what I remember of the notes of the authors of this forum, I think that I might clean that MAF sensor. Low system voltage can give you strange happenings with codes and this is a test that did not ring true for the computer, so I would give my battery a load test, and check the alternator voltage for proper output voltage. An improper voltage could easily mess up the test that turns on DTC codes. If this happens only after letting the vehicle sit for a few days then my very first checks would be a battery load test especially after sitting for a few days and alternator output voltage check. If the battery is low after sitting for a few days then load check it after a fresh charge and if that is okay then check for battery drain with the key off.

Good luck.

 

Hi Aqua,

it gets driven daily, but the battery is a few years old - still, it always starts right up, etc...

So you don't feel it's a bad O2 sensor? I'll try all the easier stuff first, including spraying that MAF sensor - I haven't really touched it in a couple of years, and that is about the last time I changed the air filter too...

It's just strange that the code didn't make it one drive cycle - usually, most of the time, if it's an evap code, it will not come back for at least a month... (again, daily driver)

What product do you like for cleaning the MAF? - I don't want to ruin it, since I know it is fragile.

Thanks

 

Sit down, read and learn... before you throw $$$ away

Cleaning the MAF - solving overdrive problems

 

Based upon the code you have, and the fact you got a P0420 code, you need to stop dancing around this issue. You have a 99% chance of multiple failed O2 sensors. Vacuum leaks result in lean codes. You don't have a lean code. Your O2 sensors are running on borrowed time, and the code confirms, they are toast.

Best case scenario, you can run them longer and end up replacing the O2 sensors later, but you will get stuck with replacing your converters too. This is not cheap or fun. You are getting the P0420 code because your crappy sensors are at the very least are making it harder for the converters to function correctly, and could be suffering permanent damage.

As I mentioned, if you put this off, it is going to cost you. The computer does not set codes for faulty O2 sensors lightly. If it sets a code, it is telling you they are very bad. I deal with this every day, catalytic converters toasted by faulty sensors, most of which aren't setting codes. If the converters can be damaged by bad sensors that don't trigger codes, imagine what a sensor that does set codes can do. if you are lucky, the computer will start ignoring the bad sensors, which acts as damage control.

 

Yeah, I kinda planned on replacing the upstream drivers side one ASAP - it just threw this code a few days ago. - wow, I don't want to kill the CC - are all three of these easily accessible from under the truck? - I see a couple of things right at the Ex Manifold on the drivers side, the first looks like it goes or is connected to vacuum lines for the Evap system - is the O2 sensor past the flange there, down closer to the front of the cat?

I might as well do them all, so any advice on getting at all three of them is welcomed

Thanks

What's the best way to get at these? do I need the special socket? or can I use just use

 

or can I just use a box wrench? or?

Thanks