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I got the P0420 code,

The car is running okay.

The guy at the auto parts store suggested Cataclean. It is only $25 so it seems worth a try.

But if it doesn’t work should I try an independent shop or go to the dealer?

My car is a 2012 at about 164k miles.

Thanks.
 

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I got the P0420 code,

The car is running okay.

The guy at the auto parts store suggested Cataclean. It is only $25 so it seems worth a try.

But if it doesn’t work should I try an independent shop or go to the dealer?

My car is a 2012 at about 164k miles.

Thanks.
I too have the same question. I got the P0420, Bank 1, efficiency below threshold. I have 223K. Seems to run fine but at time the engine shivers a little. Hopefully someone rings in.
 

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The way to check for this is to use a scanner and monitor the oxygen sensor and watch what it's doing. If it's moving up and down it's working, and is properly your converter. If the sensor numbers don't move around for the oxygen sensor and basically sit still the sensor is bad.

So basically the only way to really diagnose this is with a scanner that can read live data.

Sent from my LG-LS997 using Tapatalk
 

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The way to check for this is to use a scanner and monitor the oxygen sensor and watch what it's doing. If it's moving up and down it's working, and is properly your converter. If the sensor numbers don't move around for the oxygen sensor and basically sit still the sensor is bad.

So basically the only way to really diagnose this is with a scanner that can read live data.

Sent from my LG-LS997 using FF Mobile
I have an ELM327 OBDII Bluetooth Scanner and I have an app that allows me to read live data so I'm going to give it a try in the morning. Fingers crossed that it's a sensor and not the catalytic converter. The Focus has a ton of miles on it, 223K, but it seems like it was really taken care of quite well. So I hope it is just a sensor.
 

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I got the P0420 code,

The car is running okay.

The guy at the auto parts store suggested Cataclean. It is only $25 so it seems worth a try.

But if it doesn’t work should I try an independent shop or go to the dealer?

My car is a 2012 at about 164k miles.

Thanks.
Bad cat(s)
Bad O2 sensor(s)
Exhaust leak

I would check the output voltages of the upstream and downstream O2 sensors. Upstream should cycle ~ 0.1vdc to ~ 0.9vdc. Downstream should settle out at ~ 0.5 vdc.

Paul
 

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The guy at the auto parts store suggested Cataclean. It is only $25 so it seems worth a try.
You should attempt to diagnose the sensors (replies above). If you're just going to throw parts/money at it, I'd replace the upstream sensor ($52 at Rock Auto) before the $25 cat thing. At your miles, the sensors are likely shot.
 

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You should attempt to diagnose the sensors (replies above). If you're just going to throw parts/money at it, I'd replace the upstream sensor ($52 at Rock Auto) before the $25 cat thing. At your miles, the sensors are likely shot.
The original thread starter had 164K and was contemplating throwing a $25 bottle of cataclean in his car. I have 223K and wasn't thinking about dumping that into my tank. I've been terribly busy but tomorrow I'm taking the day off and I'll be testing the o2 sensors. Also, every once in awhile if I'm in lets say "overdrive" and I push the gas down decently hard but not hard enough to downshift, the Focus can make a throaty sound which I'm not heard in a 4 cylinder engine before. It was kinda cool but not if it's going to make my check engine light come on. I will diagnose more tomorrow. Thanks everyone!
 

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Cataclean is simply a lot of xylene and acetone, it cannot fix a converter past a few minutes while it is running in the fuel, it lower emissions hugely then but CANNOT fix the cat past the result of running it. The pics on the Holley website of a clean to the metal cat after using it are accurate if you know they soaked the cat in the stuff for hours, that WILL clean off the soot but you don't have that option running it in the fuel. Read the MSDS, it clearly tells you.
 

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The original thread starter had 164K and was contemplating throwing a $25 bottle of cataclean in his car. I have 223K and wasn't thinking about dumping that into my tank. I've been terribly busy but tomorrow I'm taking the day off and I'll be testing the o2 sensors. Also, every once in awhile if I'm in lets say "overdrive" and I push the gas down decently hard but not hard enough to downshift, the Focus can make a throaty sound which I'm not heard in a 4 cylinder engine before. It was kinda cool but not if it's going to make my check engine light come on. I will diagnose more tomorrow. Thanks everyone!
You never stated what year/model/engine/trans you have?

Paul
 

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Cataclean is simply a lot of xylene and acetone, it cannot fix a converter past a few minutes while it is running in the fuel, it lower emissions hugely then but CANNOT fix the cat past the result of running it. The pics on the Holley website of a clean to the metal cat after using it are accurate if you know they soaked the cat in the stuff for hours, that WILL clean off the soot but you don't have that option running it in the fuel. Read the MSDS, it clearly tells you.
I understand. I never was planning on running a bottle of this stuff through my car. The thread starter was thinking about it, not me.
 

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You never stated what year/model/engine/trans you have?

Paul
I don't know much about Focus cars yet. I have a 2012 Focus Hatchback Titanium. It has 223K. Yes 223K. Runs and drives like new. The engine light went away today and it still is driving great but I know I still need to test the o2 sensors while the car is running. I have a Duratec 2.0 4 Cylinder. Not sure what the model is. I have the weird DPS6 or DSP6 transmission but it seems to be working well (knock on wood). I paid $1400 for it and it's loaded with all the bells and whistles. You can even see the leather looks brand new instead of looking like 223K. The body looks great and suspension feels like new. Pics:
 

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Looks great!

At 223K I would not be surprised if your catcon issue is really a lazy/dying O2 sensor issue as I listed in my previous post. Should be easy to check with a scanner looking at live data.

Let us know
Paul
 

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I have a 2016 Escape. I had a P0420 code but it wasn’t from the cat or O2 sensor. Two different shops said my fuel pressure was too high. They couldn’t figure out why. It ended up being a gummed fuel rail and partially clogged injectors. I fixed it with K100, a fuel stabilizer. The gum was from the ethanol in our fuel.
Though my mileage was 55k when this happened.


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The way to check for this is to use a scanner and monitor the oxygen sensor and watch what it's doing. If it's moving up and down it's working, and is properly your converter. If the sensor numbers don't move around for the oxygen sensor and basically sit still the sensor is bad.

So basically the only way to really diagnose this is with a scanner that can read live data.

Sent from my LG-LS997 using FF Mobile


Ok so today I hooked up my bluetooth OBDII scanner and read some live data. Oxygen Sensor 1 and Oxygen Sensor 2 report different things? Or maybe I need a better Android Scanner? I have a few free scanner apps but none of them would give me live data and the one that did give me data, was confusing.

Here is the live data that I got. Oxygen Sensor 1 Wide Range Current WAS moving around but Oxygen Sensor 2 didn't have a current category. I did notice that Oxygen Sensor 2 has Short Term Fuel Trim that says N/A.
 

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You have to be able to see the swings in absolute highs and lows there and more importantly the amounts of swing to be able to tell the sensor action, only graphing can show that.

I question the validity of the 420 code given on the Escape, should have been showing lean codes or fuel trim limits instead for injectors clogged up. They show much faster than a 420 does.
 

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Ok so today I hooked up my bluetooth OBDII scanner and read some live data. Oxygen Sensor 1 and Oxygen Sensor 2 report different things? Or maybe I need a better Android Scanner? I have a few free scanner apps but none of them would give me live data and the one that did give me data, was confusing.



Here is the live data that I got. Oxygen Sensor 1 Wide Range Current WAS moving around but Oxygen Sensor 2 didn't have a current category. I did notice that Oxygen Sensor 2 has Short Term Fuel Trim that says N/A.
It would be hard to diagnose without live data.

Sent from my LG-LS997 using Tapatalk
 

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It would be hard to diagnose without live data.

Sent from my LG-LS997 using FF Mobile
This actually was live data, I just took a screenshot of it. The current of the one oxygen sensor was moving between 0.02 to 0.09 which is what I told it should do. However the other oxygen sensor does not measure that. There were other numbers moving too. I couldn't make a video of it. I'm questioning why one of the o2 sensors gave a N/A message?

If I now need a graph, can anyone recommend an Android OBDII app that will do this?

I will say this, and I don't want to derail people from thinking what my problem is, but my exhaust can get loud at times. Not when I hit the gas down hard, but for example, if the car is in an overdrive gear and I get on the gas enough that it doesn't shift down but it does make a deep throaty exhaust note. Might be normal or might be a leak? Maybe a donut gasket.

But what I'd like to do is rule out an o2 sensor so if anyone can recommend an app that'll do this, I'd be glad to download it. Thanks!
 

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Bank 1 sensor 2 would be the one that would trigger the code.
Bank 1 sensor 1 is the sensor before the cat. Sensor 2 is the one you need to monitor.

The reason for the NA message is because sensor 2 doesn't monitor fuel trim its only job is to monitor the effectiveness of the cat.
Sent from my LG-LS997 using Tapatalk
 

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Bank 1 sensor 2 would be the one that would trigger the code.
Bank 1 sensor 1 is the sensor before the cat. Sensor 2 is the one you need to monitor.
Sent from my LG-LS997 using FF Mobile
Sensor 2 bank 1 only measures Voltage and short term fuel trim which it says N/A. Should it be measuring current as well? This is why I think I need a different app for scanning live data. I'd even be willing to pay for an app that does this.
 

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Sensor 2 bank 1 only measures Voltage and short term fuel trim which it says N/A. Should it be measuring current as well? This is why I think I need a different app for scanning live data. I'd even be willing to pay for an app that does this.
This video explains it pretty well but yeah you need to be able to monitor the voltage of sensor 2. It sounds like sensor one is working just fine.

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