Queston regarding CHECK ENGINE
09-21-2010, 03:36 PM
#1
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Queston regarding CHECK ENGINE
Check engine light has come on three times since last spring. The first time after a relatively short trip. The lamp was lit outside the garage at idle. The last two times during moving queues. All emission values are perfect.
This is the error code:
Error code 40 catalyst cyl 1-3 poor performance. (translation from Swedish)
As I understand it there is one sensor before the catalytic converter and one after. The Porsche mechanic said it could be a leak between the sensor before the catalyst and the catalyst. He also said that the catalyst may be about to get worse performance and the engine was in such good condition that it was not noticeable. If you do not end up in a queue that is. Now the check engine light come on three occasions. I was hoping it was an isolated event. The Porsche mechanic said that the only way was to change the catalyst, but there was nothing I should care about as long as the exhaust values are perfect. Was down at the Nurburgring a week and drove back and forth to Sweden. The lamp was lit in a "stau", ie a queue in English on the Autobahn on the way home. The lamp will not light up every time you find yourself in a queue. Far from it. Three times during the season, however, is quite annoying.
I have seen that there are a lot of experience here on the forum. Maybe someone has experienced something similar? According to Porsche mechanic, it is not unusual on the 993.
This is the error code:
Error code 40 catalyst cyl 1-3 poor performance. (translation from Swedish)
As I understand it there is one sensor before the catalytic converter and one after. The Porsche mechanic said it could be a leak between the sensor before the catalyst and the catalyst. He also said that the catalyst may be about to get worse performance and the engine was in such good condition that it was not noticeable. If you do not end up in a queue that is. Now the check engine light come on three occasions. I was hoping it was an isolated event. The Porsche mechanic said that the only way was to change the catalyst, but there was nothing I should care about as long as the exhaust values are perfect. Was down at the Nurburgring a week and drove back and forth to Sweden. The lamp was lit in a "stau", ie a queue in English on the Autobahn on the way home. The lamp will not light up every time you find yourself in a queue. Far from it. Three times during the season, however, is quite annoying.
I have seen that there are a lot of experience here on the forum. Maybe someone has experienced something similar? According to Porsche mechanic, it is not unusual on the 993.
09-21-2010, 04:17 PM
#3
Rennlist Member
in a ROW turbo, there are two individual catalysts for each bank of engine 1-3 or 4-6.
Each catalyst has two O2 sensors, one before and one after.
To lightly explain, the O2 sensors after the catalysts are here to monitor the action of depollution done by the catalyst among other things.
This is done by the delta, the difference of voltages sent by the O2 sensors before and after the catalyst to the DME.
More oxygen ratio in the gas, heats the platinum filament more in the O2 sensor, that becomes elongated and thinner thus electric ohm is greater.
error code 40 or P0420 is caused by out of normal differences of electric signals between the two O2 sensors.
two alternatives here:
either your catalyst is dead, or one of the O2 sensors is sick.
In my personal experience, Turbo 993 are prone to eat an O2 sensor, before eating a catalyst.
what I would do to try to pinpoint the problem, is switching the 02 sensors
the before catalyst of 1-3 to after catalyst 4-6
the before catalyst of 4-6 to after catalyst of 1-3
this is because the O2 sensors are exactly the same, but different part numbers because of length of
electric cables.
if you have error 45 or P0430, it is the catalyst
if you have errors 26 or 27 or 34 or 35, it is the O2 sensor
O2 sensor is around 100, so no problem to change
but catalyst, you have to change because if it burns, it cracks into small pieces as large as golf *****, and go to the mufflers and burn the inside of the mufflers. Ask me how I know
regards
Each catalyst has two O2 sensors, one before and one after.
To lightly explain, the O2 sensors after the catalysts are here to monitor the action of depollution done by the catalyst among other things.
This is done by the delta, the difference of voltages sent by the O2 sensors before and after the catalyst to the DME.
More oxygen ratio in the gas, heats the platinum filament more in the O2 sensor, that becomes elongated and thinner thus electric ohm is greater.
error code 40 or P0420 is caused by out of normal differences of electric signals between the two O2 sensors.
two alternatives here:
either your catalyst is dead, or one of the O2 sensors is sick.
In my personal experience, Turbo 993 are prone to eat an O2 sensor, before eating a catalyst.
what I would do to try to pinpoint the problem, is switching the 02 sensors
the before catalyst of 1-3 to after catalyst 4-6
the before catalyst of 4-6 to after catalyst of 1-3
this is because the O2 sensors are exactly the same, but different part numbers because of length of
electric cables.
if you have error 45 or P0430, it is the catalyst
if you have errors 26 or 27 or 34 or 35, it is the O2 sensor
O2 sensor is around 100, so no problem to change
but catalyst, you have to change because if it burns, it cracks into small pieces as large as golf *****, and go to the mufflers and burn the inside of the mufflers. Ask me how I know
regards
09-21-2010, 05:34 PM
#4
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error code 40 or P0420 is caused by out of normal differences of electric signals between the two O2 sensors.
two alternatives here:
either your catalyst is dead, or one of the O2 sensors is sick.
In my personal experience, Turbo 993 are prone to eat an O2 sensor, before eating a catalyst.
what I would do to try to pinpoint the problem, is switching the 02 sensors
the before catalyst of 1-3 to after catalyst 4-6
the before catalyst of 4-6 to after catalyst of 1-3
this is because the O2 sensors are exactly the same, but different part numbers because of length of
electric cables.
if you have error 45 or P0430, it is the catalyst
if you have errors 26 or 27 or 34 or 35, it is the O2 sensor
O2 sensor is around 100, so no problem to change
but catalyst, you have to change because if it burns, it cracks into small pieces as large as golf *****, and go to the mufflers and burn the inside of the mufflers. Ask me how I know
regards
two alternatives here:
either your catalyst is dead, or one of the O2 sensors is sick.
In my personal experience, Turbo 993 are prone to eat an O2 sensor, before eating a catalyst.
what I would do to try to pinpoint the problem, is switching the 02 sensors
the before catalyst of 1-3 to after catalyst 4-6
the before catalyst of 4-6 to after catalyst of 1-3
this is because the O2 sensors are exactly the same, but different part numbers because of length of
electric cables.
if you have error 45 or P0430, it is the catalyst
if you have errors 26 or 27 or 34 or 35, it is the O2 sensor
O2 sensor is around 100, so no problem to change
but catalyst, you have to change because if it burns, it cracks into small pieces as large as golf *****, and go to the mufflers and burn the inside of the mufflers. Ask me how I know
regards
The limits in parentheses.
CO 0.0 (0.5)
CO 2500 0.0 (0.3)
HC 002 (100)
LAMBDA 1.00 (0.97 to 1.03)
09-21-2010, 06:15 PM
#5
Rennlist Member
Robert, lets relook at what I wrote, and we have the answer of the cO results.
real easy;
All the machines that check cO metering in europe (and the US I presume) are hooked in on left muffler
of the car and that the operator can hop his right foot and press the gas pedal 10 - 20 seconds for the test.
logically, he doesn't hook to the right exhaust tip because it is easier for him to do the test.
BUT, your banks are seperate, and the not good ones are 1 - 3 with exhaust tip ON THE RIGHT.
so I think the test was not done on the right exhaust tip, as easy as that, regards
real easy;
All the machines that check cO metering in europe (and the US I presume) are hooked in on left muffler
of the car and that the operator can hop his right foot and press the gas pedal 10 - 20 seconds for the test.
logically, he doesn't hook to the right exhaust tip because it is easier for him to do the test.
BUT, your banks are seperate, and the not good ones are 1 - 3 with exhaust tip ON THE RIGHT.
so I think the test was not done on the right exhaust tip, as easy as that, regards
Last edited by geolab; 09-21-2010 at 06:35 PM.
09-21-2010, 06:39 PM
#6
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I've never thought of that one only measures the exhaust gas values from the left exhaust pipe. Vehicle inspection turns the hose on both tubes, but only the left contains the instrument that measures the exhaust values, then? Do not know if this is true, but it could be an explanation.
Porsche workshop also said that the exhaust gas values were perfect when they read the error code in the spring. They should be measured from the right exhaust pipe if we are to follow the logic you presented. A question I'll ask when I leave the car at the annual service in a few weeks.
Porsche workshop also said that the exhaust gas values were perfect when they read the error code in the spring. They should be measured from the right exhaust pipe if we are to follow the logic you presented. A question I'll ask when I leave the car at the annual service in a few weeks.
09-21-2010, 06:49 PM
#7
Rennlist Member
While inspection, there is only one cO meter hooked to the exhaust, I have never seen machines with two. If on your car both have been checked, then one of the O2 sensors might be the culprit
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09-21-2010, 07:04 PM
#8
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Thank you very much for your answers. I will examine how the vehicle inspection measures the exhaust values here in Sweden. Became a bit curious when I read your response. I also wonder if the Porsche workshop who read the error codes on the car tested the emission on the right exhaust. A bit annoying if they didn´t do it. Have to check in to that too.
09-23-2010, 03:10 PM
#9
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I drove past the local vehicle inspection station and asked them how they measured emission values. They measure just from one exhaust pipe. Chance determines which. It simply depends on which side of the inspection hall you drive in. With any luck you can get a car through technical inspection, although the exhaust values is bad on one side. You learn something new every day. Hope it is just a sensor that causes trouble.
