Cat question

[Poohdaddy]

Just got a 99 Sport SOHC. MIL is giving a PO420(?) code. Bank 1 cat. The vehicle runs as smooth as glass but feels kind of down on power and very thirsty. I tried the acetone treatment and it didn't help. Can someone give me some advice on exactly which cat this is that's going out? Much appreciated

 

[rasouth]

For a while my Explorer was throwing the PO420 code and it was the result of a blown head gasket allowing coolant into the piston and burning the coolant. This caused the O2 sensor to give the PO420 code, "Catalytic efficiency below threshold". Problem could be O2 sensor or the cats. The least expensive solution would be change O2 sensors.

 

[Poohdaddy]

For a while my Explorer was throwing the PO420 code and it was the result of a blown head gasket allowing coolant into the piston and burning the coolant. This caused the O2 sensor to give the PO420 code, "Catalytic efficiency below threshold". Problem could be O2 sensor or the cats. The least expensive solution would be change O2 sensors.

How many o2 sensors are on it?

 

[RickOTR]

I won't use acetone to clean the fuel system. It can destroy rubber parts not to mention the fuel pump. IIRC there are two sensors on a 94

 

[Poohdaddy]

I won't use acetone to clean the fuel system. It can destroy rubber parts not to mention the fuel pump. IIRC there are two sensors on a 94

It's a 99. How many cats are on it?

 

[rasouth]

On my Explorer there is 3 O2 sensors, two between engine and cats and one after cats. There are two cats.

 

[96eb96]

On my Explorer there is 3 O2 sensors, two between engine and cats and one after cats. There are two cats.

Our 96 OHVs are different I think than SOHC.

 

[rasouth]

I know there is a difference between the OHV and the SOHC engines but is there a difference between the exhaust systems? I never thought about that. Good point.

 

[J_C]

It's a 99. How many cats are on it?

As shocking as it seems, at some point you are going to have to get under the vehicle and look around for things like this.

If the vehicle has never had the O2 sensors replaced, I would do that first. The code is for the passenger side O2 sensor reading after the cat, BUT if the sensor before the cat is fouled, that can throw off the fuel mix ratio and then the cat can only scrub so much so the downstream O2 sensor could be functioning fine and just reading out of range due to the upstream sensor failing, but given the age of the vehicle, I don't feel like it's shotgunning the repair as much as an inevitable part(s) replacement (instead of proper diagnosis) to replace all 3 O2 sensors since they are likely near end of life anyway, then clear codes and see if they come back.

If you really want to be minimal (labor and cost) about it, I would replace the upstream sensor before the cats first and clear the code, drive a while then see if you still get the code.

 

[Poohdaddy]

As shocking as it seems, at some point you are going to have to get under the vehicle and look around for things like this.

If the vehicle has never had the O2 sensors replaced, I would do that first. The code is for the passenger side O2 sensor reading after the cat, BUT if the sensor before the cat is fouled, that can throw off the fuel mix ratio and then the cat can only scrub so much so the downstream O2 sensor could be functioning fine and just reading out of range due to the upstream sensor failing, but given the age of the vehicle, I don't feel like it's shotgunning the repair as much as an inevitable part(s) replacement (instead of proper diagnosis) to replace all 3 O2 sensors since they are likely near end of life anyway, then clear codes and see if they come back.

If you really want to be minimal (labor and cost) about it, I would replace the upstream sensor before the cats first and clear the code, drive a while then see if you still get the code.

Yes I plan to do a visual inspection soon. There was heavy rain/sleet all weekend making it impossible to check it out. Thank you for tge input

 

[Poohdaddy]

Exhaust arrangement on your 1999 V6~4.0L~SOHC may be similar to my 2001 V6~4.0L~SOHC, pictured below.
Again take a backcrawl underneath to confirm.
Hardest part about replacing OxygenSensors is disconnecting+reconnecting HarnessPlugs:
RghtUpStream between the Engine+FireWall, LeftUpStream above the TrannyShiftCable.
View attachment 327158

OxygenSensor PartNumbers & Install Details at

Engine Exhaust OxygenSensors

This 2001 Ford ExplorerSportTrac & V6~4.0L~SOHC engine has 3 OxygenSensors; they are also known as HEGO\HeatedExhaustGasOxygen, H02\HeatedOxygen, Lambda\NarrowBand Sensors; as located below. Sensor11+Sensor21, pic below, are between Rght+LeftManifolds & Rght+LeftCatConvertors, respectively...

2001fordexplorersporttrac.fandom.com

Hope this helps.

 

[Poohdaddy]

Excellent. Thank you sir

 

[German Engineer]

Hook up an OBDII scanner and look at the live data. It should give you an idea if the two upstream o2 sensors are functioning normally or if they're sluggish. The third downstream one behind the cat should give you an idea if the cat works or not.
Fuel trim values should also help give you a general idea.

There's plenty of videos on Youtube that explain what to look for and what voltage ranges you'll want to see in the live data from the sensors.

That's what I'd do first to diagnose and narrow the issue down.

 

[Poohdaddy]

Hook up an OBDII scanner and look at the live data. It should give you an idea if the two upstream o2 sensors are functioning normally or if they're sluggish. The third downstream one behind the cat should give you an idea if the cat works or not.
Fuel trim values should also help give you a general idea.

There's plenty of videos on Youtube that explain what to look for and what voltage ranges you'll want to see in the live data from the sensors.

That's what I'd do first to diagnose and narrow the issue down.

Good idea. The hardest part is getting my hands on scanner

 

[German Engineer]

Good idea. The hardest part is getting my hands on scanner

You can get cheap ones that work well with Forscan for under 40 bucks already.
Even if you spend more on something better than the most basic models, it's an investment that's well worth it and will save you money on multiple occasions.

 

[Poohdaddy]

You can get cheap ones that work well with Forscan for under 40 bucks already.
Even if you spend more on something better than the most basic models, it's an investment that's well worth it and will save you money on multiple occasions.

Do you have a link to a good affordable one?

 

[German Engineer]

Do you have a link to a good affordable one?

That depends on what you want to do with it and there's constantly new offers and models.

I have a stand alone one that's compatible with a whole range of vehicles and can read out ABS SRS codes from most US vehicles.
The one I have is the AutoLink Autel AL619 and you can get it for around $100.

If you just need one for your Explorer or Ford vehicles then anything that works good with Forscan is cheap and good and can usually do even more than mine.

I almost purchased another one because of problems with my RAP module.
I didn't end up buying one, so I really can't make a recommendation for one, but these two looked pretty good to me then:
https://www.amazon.com/dp/B081VQVD3F/?tag=serious-20
https://www.amazon.com/dp/B089WD7NYB/?tag=serious-20

The Autel Al619 one I mentioned above is one I'm very happy with and I haven't had any issues with it in almost 5 years now and I've used it on numerous vehicles from several brands saving myself, friends and neighbors more then ten times what I spent on it. The gifts and money/tips some of them offered and gave me in return for my help alone already paid for it more than three times by now.

 

[Poohdaddy]

That depends on what you want to do with it and there's constantly new offers and models.

I have a stand alone one that's compatible with a whole range of vehicles and can read out ABS SRS codes from most US vehicles.
The one I have is the AutoLink Autel AL619 and you can get it for around $100.

If you just need one for your Explorer or Ford vehicles then anything that works good with Forscan is cheap and good and can usually do even more than mine.

I almost purchased another one because of problems with my RAP module.
I didn't end up buying one, so I really can't make a recommendation for one, but these two looked pretty good to me then:
https://www.amazon.com/dp/B081VQVD3F/?tag=serious-20
https://www.amazon.com/dp/B089WD7NYB/?tag=serious-20

Excellent. I'm mainly looking one I can read live data for my explorer. Many thanks

 

[J_C]

I use one of these:
https://www.amazon.com/dp/B005NLQAHS/?tag=serious-20

OR if you also need to use it with an iphone or other apple tablet/etc then get the wifi version:
https://www.amazon.com/dp/B078K54MT5/?tag=serious-20

This type is VERY handy to be able to use with your phone. I leave it in the glovebox so can use it anywhere at any moment. You can use Forscan and/or Torque apps. There are others but these two are the best of the bunch. Both of these apps have a free version, Forscan being the better of the two for Ford vehicles, but only the paid version of Forscan can reset codes while the free version of Torque can. Fortunately, it's no problem to have both on a phone, tablet or whatever.

You can get cheaper ELM327 based products but the quality tends to be worse and some don't even read the J1850 protocol that our generation of Explorers uses, despite claiming they work with all OBDII vehicles.

 

[Poohdaddy]

I use one of these:
https://www.amazon.com/dp/B005NLQAHS/?tag=serious-20

OR if you also need to use it with an iphone or other apple tablet/etc then get the wifi version:
https://www.amazon.com/dp/B078K54MT5/?tag=serious-20

This type is VERY handy to be able to use with your phone. I leave it in the glovebox so can use it anywhere at any moment.

You can get cheaper ELM327 based products but the quality tends to be worse and some don't even read the J1850 protocol that our generation of Explorers uses, despite claiming they work with all OBDII vehicles.

So that will work with a smartphone? Does it stream live data?