code p0431 help,
Thread Starter
Rennlist Member
Joined: Dec 2010
Posts: 1,972
Likes: 19
From: Morehead City NC
code p0431 help,
I have searched and cannot find the info i am looking for, so any help would be greatly appreciated.
I am getting a code for p0431, warmup camshaft efficncy below threshold bank 2
what is the warmup camshaft?
this is the code while in the porsche DME. the generic obII is just p0431 warmup catalyst efficency below threshold bank2
I am using the carsoft IPOR reader. i looked at o2 voltages and they appear to be ok.
exhaust temp after cat are 647deg.
both downstream voltages are .7v
both upstream are 2v
both lambda regulat. behind cat are 0.00%
lambda cont. correct behind cat bank 1 is -0.25%
lambda cont. correct behind cat bank 2 is -0.05%
status of catalyst bank is 1 0.07
status of catalyst bank 2 is 1
test counter for c.c diagnosis b2 0.0
test counter for c.c. diagnosos bank1 0.0
I am getting a code for p0431, warmup camshaft efficncy below threshold bank 2
what is the warmup camshaft?
this is the code while in the porsche DME. the generic obII is just p0431 warmup catalyst efficency below threshold bank2
I am using the carsoft IPOR reader. i looked at o2 voltages and they appear to be ok.
exhaust temp after cat are 647deg.
both downstream voltages are .7v
both upstream are 2v
both lambda regulat. behind cat are 0.00%
lambda cont. correct behind cat bank 1 is -0.25%
lambda cont. correct behind cat bank 2 is -0.05%
status of catalyst bank is 1 0.07
status of catalyst bank 2 is 1
test counter for c.c diagnosis b2 0.0
test counter for c.c. diagnosos bank1 0.0
Banned
Joined: Mar 2011
Posts: 10,084
Likes: 1,206
From: Spring Lake, NJ, US of A
There is no warmup camshaft. The tool has the wrong description - Generic OBD-II codes are exactly that, and not changed by the manufacturer. What that code means is "Warm Up Catalyst Efficiency Below Threshold (Bank 2)" - meaning the downstream from the cat-converter 02 sensor on bank-2 is reading too high.
This could be caused by a number of things - pretty much in descending order of probability:
1. Bad 02 sensor - could be either one - but more likely the one after the cat.. if the front one was defective - it could be telling the ECU the mixture is too lean - causing it to richen it too much - so too much gets through the cat converter.
How to tell? Plot the output of the two converters. The primary one should show a switched voltage. The secondary one probably a voltage near 1V and fairly constant. If it shows a switched voltage then:
2. Bad cat-coverter. It happens. Not too often.
3. Something else. If the above doesn't point to the source of the problem you need someone who knows fuel injection and emissions to look at it with a tool that gives both the generic OBD-II codes (and anything below P0999 is generic) and the Porsche specific codes. Preferably a tool that can also read stored fault messages that are not causing a CEL.
You mentioned:
I assume these are the 02 sensor readings?
The upstream is very improbable. The normal upstream O2 voltage switches at about 1 second intervals as it tells the ECU "rich-lean, rich-lean..) It appears as a sawtooth sort of pattern when plotted, ranging from around 1.2V+ to -0.7V. It isn't a constant voltage.
The downstream looks legit - but how long was the engine running when you took that reading? The error implies it occurs during engine warmup, which is fairly short if the O2 sensors are working and the heaters in them are working. If these values were read after the engine even partially warmed up - and it's something like a slow O2 sensor, or one where the heater circuit failed (which will mean it doesn't work until the exhaust warms it up) - the numbers are meaningless.
This could be caused by a number of things - pretty much in descending order of probability:
1. Bad 02 sensor - could be either one - but more likely the one after the cat.. if the front one was defective - it could be telling the ECU the mixture is too lean - causing it to richen it too much - so too much gets through the cat converter.
How to tell? Plot the output of the two converters. The primary one should show a switched voltage. The secondary one probably a voltage near 1V and fairly constant. If it shows a switched voltage then:
2. Bad cat-coverter. It happens. Not too often.
3. Something else. If the above doesn't point to the source of the problem you need someone who knows fuel injection and emissions to look at it with a tool that gives both the generic OBD-II codes (and anything below P0999 is generic) and the Porsche specific codes. Preferably a tool that can also read stored fault messages that are not causing a CEL.
You mentioned:
Originally Posted by yardpro
both downstream voltages are .7v
both upstream are 2v
both upstream are 2v
The upstream is very improbable. The normal upstream O2 voltage switches at about 1 second intervals as it tells the ECU "rich-lean, rich-lean..) It appears as a sawtooth sort of pattern when plotted, ranging from around 1.2V+ to -0.7V. It isn't a constant voltage.
The downstream looks legit - but how long was the engine running when you took that reading? The error implies it occurs during engine warmup, which is fairly short if the O2 sensors are working and the heaters in them are working. If these values were read after the engine even partially warmed up - and it's something like a slow O2 sensor, or one where the heater circuit failed (which will mean it doesn't work until the exhaust warms it up) - the numbers are meaningless.
Thread Starter
Rennlist Member
Joined: Dec 2010
Posts: 1,972
Likes: 19
From: Morehead City NC
Thanks... I'll give it a shot.
you are correct about the pre cat voltages... running data stream it does fluctuate.
These se readings were taken when engine was warm, 205 degree water temp.
wife had been shopping and got home so I went out to check it out.
ill try the sea foam
thx
you are correct about the pre cat voltages... running data stream it does fluctuate.
These se readings were taken when engine was warm, 205 degree water temp.
wife had been shopping and got home so I went out to check it out.
ill try the sea foam
thx
Rennlist Member
Joined: Mar 2012
Posts: 17,250
Likes: 2,219
From: SoCal
99% of the time those codes are for bad 02 sensor (post and possibly pre cat) or Catalyst.
you can swap the post-cat left/right and see if the error follows the change. if so, bad sensor, if not, most likely inefficient cat.
you can swap the post-cat left/right and see if the error follows the change. if so, bad sensor, if not, most likely inefficient cat.
Three Wheelin'
Joined: May 2014
Posts: 1,768
Likes: 192
There is no warmup camshaft. The tool has the wrong description - Generic OBD-II codes are exactly that, and not changed by the manufacturer. What that code means is "Warm Up Catalyst Efficiency Below Threshold (Bank 2)" - meaning the downstream from the cat-converter 02 sensor on bank-2 is reading too high.
This could be caused by a number of things - pretty much in descending order of probability:
1. Bad 02 sensor - could be either one - but more likely the one after the cat.. if the front one was defective - it could be telling the ECU the mixture is too lean - causing it to richen it too much - so too much gets through the cat converter.
How to tell? Plot the output of the two converters. The primary one should show a switched voltage. The secondary one probably a voltage near 1V and fairly constant. If it shows a switched voltage then:
2. Bad cat-coverter. It happens. Not too often.
3. Something else. If the above doesn't point to the source of the problem you need someone who knows fuel injection and emissions to look at it with a tool that gives both the generic OBD-II codes (and anything below P0999 is generic) and the Porsche specific codes. Preferably a tool that can also read stored fault messages that are not causing a CEL.
You mentioned:
I assume these are the 02 sensor readings?
The upstream is very improbable. The normal upstream O2 voltage switches at about 1 second intervals as it tells the ECU "rich-lean, rich-lean..) It appears as a sawtooth sort of pattern when plotted, ranging from around 1.2V+ to -0.7V. It isn't a constant voltage.
The downstream looks legit - but how long was the engine running when you took that reading? The error implies it occurs during engine warmup, which is fairly short if the O2 sensors are working and the heaters in them are working. If these values were read after the engine even partially warmed up - and it's something like a slow O2 sensor, or one where the heater circuit failed (which will mean it doesn't work until the exhaust warms it up) - the numbers are meaningless.
This could be caused by a number of things - pretty much in descending order of probability:
1. Bad 02 sensor - could be either one - but more likely the one after the cat.. if the front one was defective - it could be telling the ECU the mixture is too lean - causing it to richen it too much - so too much gets through the cat converter.
How to tell? Plot the output of the two converters. The primary one should show a switched voltage. The secondary one probably a voltage near 1V and fairly constant. If it shows a switched voltage then:
2. Bad cat-coverter. It happens. Not too often.
3. Something else. If the above doesn't point to the source of the problem you need someone who knows fuel injection and emissions to look at it with a tool that gives both the generic OBD-II codes (and anything below P0999 is generic) and the Porsche specific codes. Preferably a tool that can also read stored fault messages that are not causing a CEL.
You mentioned:
I assume these are the 02 sensor readings?
The upstream is very improbable. The normal upstream O2 voltage switches at about 1 second intervals as it tells the ECU "rich-lean, rich-lean..) It appears as a sawtooth sort of pattern when plotted, ranging from around 1.2V+ to -0.7V. It isn't a constant voltage.
The downstream looks legit - but how long was the engine running when you took that reading? The error implies it occurs during engine warmup, which is fairly short if the O2 sensors are working and the heaters in them are working. If these values were read after the engine even partially warmed up - and it's something like a slow O2 sensor, or one where the heater circuit failed (which will mean it doesn't work until the exhaust warms it up) - the numbers are meaningless.
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1st Gear
Joined: Jul 2020
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p0421 p0431
hi, I have a 2012 911 3.6lt with codes po421 and p0431 that come on at the same time always after about 500 miles after clearing the codes. dealer replaced both upstream o2 sensors still not fixed...any ideas?
Rennlist Member
Joined: Jan 2010
Posts: 5,108
Likes: 397
From: Oneida, New York
both faults recurring on my DD.. factory .Pcar tech says primary cats are failing. 130k miles, 1/3-1/2 qt per 1000miles oil usage. Been chasing CEL’s for almost 2 years, evap issues, then bank 2 downstream O2, now this. These two faults reared their ugly heads within a couple hundred miles of that downstream O2 sensor change.
