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2001 Sable P0420


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#1 seachunk2

 
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Posted 27 February 2012 - 07:54 PM

I get the P0420 (Cat Converter below efficiency threshold) on my 2001 Sable 3.0L Duratec. It seems that if I fully warm up the car from a cold start (temps are around 30 degrees overnight) and then get on the nearby parkway that's 1 mile away, I'll throw the engine light within a few miles after getting to about 50 mph with the cruise control engaged. However, if I clear the code, the MIL rarely comes on for the rest of the day.
The car runs fine. It idles smooth as hell, (like new) even though it has 122,000 miles. I get 20 MPG combined city/highway driving.
The rear O2 sensor is original and I might replace it and see what happens.

Question- if the car runs great and the mpg is good, how likely is it that the cat is no good?

#2 fullsizeblazin

 
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Posted 27 February 2012 - 10:36 PM

A P0420 is a pretty good indication of a bad catalytic convertor. The best way is to monitor the front and rear 02 sensor PIDS and if they are similar after the cat is fully warmed up, then the cat is officially no good.. Be pricing out a Cat, you're gonna be replacing it.

#3 Saltmine

 
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Posted 27 February 2012 - 11:45 PM

A P0420 is indicating the rear oxygen sensor is not showing the desired trend when the ECU compares it to the front sensor, so it sets a code because it "thinks" the converter isn't cleaning up the exhaust enough. Too many guys dive into this code thinking it's "just the cat" and soon find out that there was some underlying reason for it to set the code.
If that Taurus with a nicer dress on is only returning 20mpg there's got to be something wrong with the fuel system..maybe a leaking injector or pressure regulator, or whatever.

My Chevy get's over 30mpg, and it weighs more than a Sable and has about the same size engine. Fuel system....I think there's some raw fuel going out the exhaust, making the rear oxygen sensor think the cat's bad.

But, if you have to be convinced, go ahead and buy a new catalytic converter, slap it on, and clear the code.....We'll see how long it takes for the code to reset.
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#4 Karrpilot

 
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Posted 28 February 2012 - 06:42 AM

The rear O 2 sensors should basically be flat lining on their voltage output. Meaning, a VERY slow voltage change. As opposed to the front 0 2 sensors.

IF the rear sensor(s) are switching voltages like the front sensors are, than yes. Your converter has, or is, failing. That being said, Ford has had PCM issues reguarding this problem. My suggesstion is to make sure you have the latest and greatest PCM file update BEFORE you toss a set of converters at it.

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#5 Saltmine

 
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Posted 28 February 2012 - 10:28 AM

That being said.....What is an eleven-year-old Mercury Sable worth? With 122,000 miles on it? Probably not worth the price of a pair of cats.....
Sam Will
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#6 Karrpilot

 
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Posted 28 February 2012 - 05:56 PM

No, and aftermarket converters, although usually less than 1/2 what Ford wants for them, only last 2-3 years. Most times, what happens is the lower intake gaskets leak. This in turn causes the fuel ratio to go lean. And burn up the converters over time.

My suggestion is to clear the codes, and trade the car in that very same day. You will take a beating on the trade, but you could also take a beating throwing converters and a set of intake gaskets at it. Only to have a trans or engine fail somewhere down the line.

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#7 seachunk2

 
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Posted 28 February 2012 - 07:41 PM

I had an Actron Scanner hooked up for the past 2 days while I drove 20 miles each way to work (30 minutes ride each way). In the 80 or so miles of driving I did, the MIL never went on. I monitored the upstream & downstream O2 readings and the voltage fluctuated on both banks. I can't say that the downstream reading was any flatter than the upstream. Most of the driving was at 25 to 50 mph stopping at several lights along the way. There wasn't any highway driving but there were spurts where I might of covered close to a mile or so at a steady 45 mph.

I would have expected the MIL to go off but it hasn't. So, if the cat is bad, wouldn't the MIL of come on at some point?
Why am I able to go 100 or so miles before it does? I'm curious to see how many miles before the next MIL.

As I mentioned, this car runs excellent in every way. I don't consider the 20 mpg I'm getting to be too low considering I'm often driving at lower speeds in the winter with stop and go. I doubt I'd throw the cats in the car considering what that would cost and what the car is worth. I'll clean the MAF sensor this weekend.

#8 Saltmine

 
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Posted 28 February 2012 - 11:06 PM

Beware of aftermarket cats. Most of the "bargain" cats are very low restriction and don't do anything to catalyze the exhaust stream...BT, DT. Had to take a car back twice to have the cat replaced because the P0420 kept resetting, even after two new cats. I finally got an OBD2 certified catalytic converter, and that cured the problem.
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#9 seachunk2

 
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Posted 02 March 2012 - 07:56 PM

Some facts...
I bought a cheapo Harbor Freight Infrared temp gun and took a temp reading at each cat from the front and rear side.
The cat just behind the radiator read 211 degree on the upstream side and 311 on the downstream. A solid 100 degree difference.
The second cat located more or less on the passenger side but towards the rear of the engine read 185 upstream and about the same downstream.

I also ran the car with the Actron 9180 scanner on it and had it set to trigger the record data mode when a MIL went off. Here is some of the data:
Frame 1 Mod $10
TROUB CODE P0420
ENG SPEED RPM 1814
CALC LOAD % 32.1
COOLANT F 192
ST FTRM1 % 3.1

Since DTCs Cleared
Misfire Monitor ok
Fuel System Mon ok
Comp Component ok
Catalyst Mon ok
Htd Catalyst n/a
Evap System Mon inc
Sec Air System n/a
A/C Refrig Mon n/a
Oxygen Sens Mon ok
Oxygen Sens Htr ok
EGR System Mon ok


Non OBD State OBD Check

MIL Status: OFF
Codes Found: 0
Monitors OK: 7
Monitors Inc: 1
Monitors N/A: 3

Frame 1 Mod $10
TROUB CODE P0420
ENG SPEED RPM 1814
CALC LOAD % 32.1
COOLANT F 192
ST FTRM1 % 3.1
LT FTRM1 % -3.4
ST FTRM2 % 3.9
LT FTRM2 % -2.2
ST FTRM3 % -54.6
LT FTRM3 % -72.9
LT FTRM4 % -57.5
ST FTRM4 % -63.3
VEH SPEED MPH 48
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2 Monitors

Vehicle did not
return data for any
O2 Monitor Tests

(Note: the following tests came in as NOT OK or out of the min-max range, all other tests were OK so I didn't include them to minimize this post. )

Test $10

ID: 11
MAX: 32
MEAS: 37
MIN: ----
STS: HI
MOD: $10

Test $2a

ID: 00
MAX: ----
MEAS: 0
MIN: 8400
STS: LOW
MOD: $10


Test $2b

ID: 00
MAX: ----
MEAS: 0
MIN: 8a00
STS: LOW
MOD: $10

Test $56

ID: 00
MAX: bb8
MEAS: 165e
MIN: ----
STS: HI
MOD: $10

(On the next post, I'll include data once the MIL went on)


Question for now, is the radiator side cat the #1 or #2 bank? I think it's the #2 bank. This is the side of the motor that has the 4, 5 & 6 cylinders.
The passenger/rear cat is what I believe is the #1 bank. (that where the 1,2 & 3 cylinders are located. If this is correct, and looking at the temp reading I was getting, it appears that the bank #1 cat is a gonner.
The bank #2 cat might still be OK. Is there any chance that I'm correct? Is there any chance it's something inexpensive (like the downstream O2 sensor is no good? I know...keep dreaming...)

#10 seachunk2

 
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Posted 02 March 2012 - 08:46 PM

here is the data with the MIL illuminated-

MIL STATUS ON
ABSLT TPS % 18.8
ENG SPEED RPM 1814
CALC LOAD % 30.9
MAF FLOW GR/SE 14.00
COOLANT F 192
IAT F 33
IGN ADVANCE DE 42.0
ST FTRM1 % -2.2
LT FTRM1 % -3.4
ST FTRM2 % -4.6
LT FTRM2 % -4.9
VEH SPEED MPH 48
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.745
ST FTRM11 % -6.3
O2S12 V 0.325
O2S21 V 0.140
ST FTRM21 % -2.2
O2S22 V 0.570
OBD2 STAT CA

Frame 1 Time 0.8


MIL STATUS ON
ABSLT TPS % 16.0
ENG SPEED RPM 1756
CALC LOAD % 18.8
MAF FLOW GR/SE 8.97
COOLANT F 192
IAT F 33
IGN ADVANCE DE 17.0
ST FTRM1 % -6.3
LT FTRM1 % -6.3
ST FTRM2 % -7.7
LT FTRM2 % -7.5
VEH SPEED MPH 45
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.100
ST FTRM11 % 0.8
O2S12 V 0.100
O2S21 V 0.835
ST FTRM21 % -7.5
O2S22 V 0.615
OBD2 STAT CA

Frame 2 Time 1.5


MIL STATUS ON
ABSLT TPS % 16.0
ENG SPEED RPM 1598
CALC LOAD % 19.6
MAF FLOW GR/SE 7.97
COOLANT F 192
IAT F 33
IGN ADVANCE DE 15.0
ST FTRM1 % 0.7
LT FTRM1 % -8.0
ST FTRM2 % -4.9
LT FTRM2 % -8.0
VEH SPEED MPH 40
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.210
ST FTRM11 % -4.6
O2S12 V 0.085
O2S21 V 0.110
ST FTRM21 % -1.0
O2S22 V 0.085
OBD2 STAT CA

Frame 3 Time 2.2


MIL STATUS ON
ABSLT TPS % 16.0
ENG SPEED RPM 1290
CALC LOAD % 20.7
MAF FLOW GR/SE 6.75
COOLANT F 192
IAT F 33
IGN ADVANCE DE 15.0
ST FTRM1 % 0.0
LT FTRM1 % -10.4
ST FTRM2 % -2.2
LT FTRM2 % -9.2
VEH SPEED MPH 28
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.800
ST FTRM11 % -3.4
O2S12 V 0.760
O2S21 V 0.770
ST FTRM21 % -6.3
O2S22 V 0.140
OBD2 STAT CA

Frame 4 Time 2.9


MIL STATUS ON
ABSLT TPS % 16.0
ENG SPEED RPM 1205
CALC LOAD % 23.1
MAF FLOW GR/SE 7.14
COOLANT F 192
IAT F 33
IGN ADVANCE DE 15.0
ST FTRM1 % 0.0
LT FTRM1 % -7.7
ST FTRM2 % -4.9
LT FTRM2 % -7.5
VEH SPEED MPH 18
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.380
ST FTRM11 % -4.6
O2S12 V 0.250
O2S21 V 0.805
ST FTRM21 % -4.9
O2S22 V 0.170
OBD2 STAT CA

Frame 5 Time 3.7


MIL STATUS ON
ABSLT TPS % 20.0
ENG SPEED RPM 1294
CALC LOAD % 54.9
MAF FLOW GR/SE 20.48
COOLANT F 192
IAT F 33
IGN ADVANCE DE 37.0
ST FTRM1 % 4.6
LT FTRM1 % 0.8
ST FTRM2 % 3.9
LT FTRM2 % 0.7
VEH SPEED MPH 16
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.165
ST FTRM11 % 4.6
O2S12 V 0.090
O2S21 V 0.160
ST FTRM21 % 4.6
O2S22 V 0.695
OBD2 STAT CA

Frame 6 Time 4.4


MIL STATUS ON
ABSLT TPS % 21.5
ENG SPEED RPM 1591
CALC LOAD % 40.0
MAF FLOW GR/SE 16.83
COOLANT F 192
IAT F 33
IGN ADVANCE DE 42.0
ST FTRM1 % 0.8
LT FTRM1 % 0.8
ST FTRM2 % 0.8
LT FTRM2 % 1.5
VEH SPEED MPH 17
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.800
ST FTRM11 % 0.0
O2S12 V 0.720
O2S21 V 0.580
ST FTRM21 % 0.8
O2S22 V 0.705
OBD2 STAT CA

Frame 7 Time 5.1


MIL STATUS ON
ABSLT TPS % 23.9
ENG SPEED RPM 1841
CALC LOAD % 44.3
MAF FLOW GR/SE 18.66
COOLANT F 192
IAT F 33
IGN ADVANCE DE 45.5
ST FTRM1 % -1.0
LT FTRM1 % -2.2
ST FTRM2 % -1.0
LT FTRM2 % -4.6
VEH SPEED MPH 19
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.750
ST FTRM11 % -4.9
O2S12 V 0.500
O2S21 V 0.520
ST FTRM21 % -5.1
O2S22 V 0.675
OBD2 STAT CA

Frame 8 Time 5.8


MIL STATUS ON
ABSLT TPS % 16.0
ENG SPEED RPM 1034
CALC LOAD % 23.5
MAF FLOW GR/SE 6.09
COOLANT F 192
IAT F 33
IGN ADVANCE DE 17.0
ST FTRM1 % -5.1
LT FTRM1 % -7.7
ST FTRM2 % -6.3
LT FTRM2 % -7.5
VEH SPEED MPH 13
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.155
ST FTRM11 % -1.0
O2S12 V 0.090
O2S21 V 0.105
ST FTRM21 % -4.6
O2S22 V 0.665
OBD2 STAT CA

#11 Karrpilot

 
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Posted 02 March 2012 - 09:43 PM

No, you are not going to get off cheap with a rear O 2 sensor. If all you had was a bad rear sensor, it would have kicked a different code. One stating swiching rate out of specs, heater circuit failure, etc. Those things. When a P0420 or a P0430 code comes up, it is time to replace the converters. They have failed.

Now the other issue is WHY have they failed? Lack of tune ups, maintenence, bad intake gaskets, MAF sensor on the far side of the range specs, etc. Even running over something and breaking apart the internal brick can cause this.

Seems to me your choices are thease. 1. Drive with the light on untill you get caught on your next emissions test. 2. Throw good money after bad getting it fixed. 3. Selling or donating the ride.

Or if you are lucky, and live in an area that does not test their cars, drive it untill it dies and the idiot light eventually will burn itself out. :lol:

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#12 Saltmine

 
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Posted 03 March 2012 - 12:20 AM

Heh, heh, heh....I looked at the scan data....See all of those minus (-) numbers on the fuel trim? The ECU is trying to pull the fuel trim back, and something isn't letting it.....like a leaking injector, a stuck EGR valve, or a saturated canister, and the IAT is sitting at a fixed value. The front oxygen sensors BOTH trending above .043V, so that verifies the fact that it's "runnin' fat".and both of the downstream sensors are reading correctly.

You can stick a couple of 'cats on it, but the data I'm seeing tells me it won't take long to burn those up in no time at all....

And yes, I'm familiar with the peculiarities of an Actron 9180 scan tool. A friend of mine has one....and I had to teach him how to use it.
Sam Will
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Kingman, Arizona
Retired

40 years of training....wasted.

#13 Saltmine

 
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Posted 04 March 2012 - 03:23 AM

I remember.....back in "the olden days"....There were a lot of Fords running around with a strategically placed piece of electrical tape (right over the "check engine light")

Some guys were even industrious enough to pull the instrument cluster and either paint the bulb black or remove it completely.
Sam Will
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Mohave County Public Works
Kingman, Arizona
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40 years of training....wasted.

#14 Karrpilot

 
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Posted 06 March 2012 - 08:09 PM

That pretty much sums it up. And why the car is only getting 20 MPG from a Taurus. But as i have stated prior, one HAS to find out WHY the converter has failed before replacing it. No use in doing the job twice, eh?

When i was fighting a driveability issue with grand ma's car 3 years ago, i found the fuel trims on the positive side. Not bad, still in specs. Furthur testings, i replaced the bad lower intake gaskets. Only to catch the rear oxygen sensors just starting to fluctuate like the front sensors.

So i know, eventually, the converters will need to be replaced. When it kicks the kiss of death codes. Since grand ma doesn't drive that much now, and the car is too old to test, a code clearing will be in order.

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#15 Saltmine

 
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Posted 07 March 2012 - 10:46 AM

I know if my eleven year old Impala started getting 20 mpg, it would be for sale the next day. It's a stubborn old bitch, 26 mpg in town, and 32 mpg out on the highway.(with the A/C on)

The last time it kicked a code.....actually the ONLY time it kicked a code, was when I replaced the spark plugs, and didn't think the wires were bad....they were, and the old gal lit up the MIL with a code P0300. New wires, and cleared the code...and that was it.
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#16 Saltmine

 
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Posted 07 March 2012 - 08:08 PM

It's pretty scary when you get a car that needs a scanner equipped with a firebox and a boiler. And you have to light it, and get up a head of steam before you can scan the car with it.

I had one of those scanners. I had to get rid of it.....Mainly because I don't know how to read Egyptian hieroglyphics
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#17 chi-tech701

 
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Posted 29 March 2012 - 10:38 AM

USEING A INFERED THEMOMETER A PROPERLY FUNCTIONING CAT IS AT LEAST 50 DEGREES WARMER ON THE OUTLET SIDE THAN THE INLET SIDE. INTAKE GASKETS USEALLY SET A LEAN CODE,CHECK MODE 6 DATA FOR ANY SLIGHT MISFIRES 99.99% OF THE TIME ITS A BAD CAT,IF YOU DONT NEED AN EMMISSION ,I WOULD IGNORE IT




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