Check Engine Light came on
07-02-2006, 09:27 AM
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Check Engine Light came on
...The code that came up was PO400 ..Has anyone had this if so what was done to fix it?
Its reffering to an EGR Problem .... That much i do know....Anyone have info for me ????
Its reffering to an EGR Problem .... That much i do know....Anyone have info for me ????
07-04-2006, 02:52 AM
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2006 ML500
PO400 meaning...
I still have my All data account open and checked on this code.
P-code means PO400: Exhauset gas recirculation circuit malfunction.
From the description and operation of the exhaust gas recirculation you need to get to a mechanic to check out the EGR system.
The EGR valve (89) is combined with an electric EGR vacuum transducer (Y31/1).
The EGR [ARF] vacuum transducer (Y31/1) stabilizes the sharply varying intake manifold vacuum and is actuated by the ME control unit by means of a PWM signal, frequency approx. 10 HZ, on/off ratio approx. 30 - 100%.
The EGR valve is opened to a varying extent as a result of this actuation with a vacuum of approx. 80 to 200 mbar and the quantity of exhaust gases which are recirculated, is controlled in this way.
The exhaust gases are recirculated in line with the map stored in the ME control unit as soon as the following conditions are met:
* Coolant temperature between 60°C and 110°C
* Engine speed <3500 rpm
* Partial load.
The map is designed to achieve optimum fuel consumption. In this case as much exhaust gas as possible is recirculated without impairing engine running or exhaust emissions.
Low-oxygen exhaust is inducted at the EGR valve, depending on the opening cross-section. As a result, the fuel-air mixture contains less oxygen. The combustion temperature drops and the formation of NOX is reduced.
The inducted air mass is reduced by the quantity of exhaust gases which are recirculated. In line with this, the ME control unit meters less fuel.
This is from All data as a description of the EGR system. I am not a mechanic and I would double check with one that knows how to get to it as it is behind the main engine and hard to get to. This is to give you more information and it is up to you on how you want to proceed.
Hopes this helps.
P-code means PO400: Exhauset gas recirculation circuit malfunction.
From the description and operation of the exhaust gas recirculation you need to get to a mechanic to check out the EGR system.
The EGR valve (89) is combined with an electric EGR vacuum transducer (Y31/1).
The EGR [ARF] vacuum transducer (Y31/1) stabilizes the sharply varying intake manifold vacuum and is actuated by the ME control unit by means of a PWM signal, frequency approx. 10 HZ, on/off ratio approx. 30 - 100%.
The EGR valve is opened to a varying extent as a result of this actuation with a vacuum of approx. 80 to 200 mbar and the quantity of exhaust gases which are recirculated, is controlled in this way.
The exhaust gases are recirculated in line with the map stored in the ME control unit as soon as the following conditions are met:
* Coolant temperature between 60°C and 110°C
* Engine speed <3500 rpm
* Partial load.
The map is designed to achieve optimum fuel consumption. In this case as much exhaust gas as possible is recirculated without impairing engine running or exhaust emissions.
Low-oxygen exhaust is inducted at the EGR valve, depending on the opening cross-section. As a result, the fuel-air mixture contains less oxygen. The combustion temperature drops and the formation of NOX is reduced.
The inducted air mass is reduced by the quantity of exhaust gases which are recirculated. In line with this, the ME control unit meters less fuel.
This is from All data as a description of the EGR system. I am not a mechanic and I would double check with one that knows how to get to it as it is behind the main engine and hard to get to. This is to give you more information and it is up to you on how you want to proceed.
Hopes this helps.
07-04-2006, 05:30 PM
#3
Originally Posted by nyml320
...The code that came up was PO400 ..Has anyone had this if so what was done to fix it?
Its reffering to an EGR Problem .... That much i do know....Anyone have info for me ????
Its reffering to an EGR Problem .... That much i do know....Anyone have info for me ????
07-05-2006, 01:20 AM
#4
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Depending on your mileage, I would replace the EGR valve and the Pipe that runs to the valve. You can always apply vacuum to the valve and see if it lower the idle to check the operation.
07-05-2006, 02:25 PM
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Replacing
Well I took off the Egr Valve pipe it was filled with some carbon ...Cleaned it all out
Then Cleaned out the EGR valve ...
Last put it all back together and cleared the system...Poped back up within 12 miles traveled...
Order a new one monday should have a new one in by thursday and see where we are at there after ......
Then Cleaned out the EGR valve ...
Last put it all back together and cleared the system...Poped back up within 12 miles traveled...
Order a new one monday should have a new one in by thursday and see where we are at there after ......
04-05-2009, 07:42 PM
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ml320
nyml320,
Just recently cleaned my EGR as well due to DTC P0400. Made sure the valve functioned smoothly but not sure if smooth enough as brand new. Reinstalled and just like you said, after about 20 miles, P0400 popped back up again.
After replacing with a new one, did it fix the P0400 issue? Also, where did u buy it and how much did it cost?
I am now planning to replace it with a new one. I followed one forum post on how to remove it but it was kind of general and did not go into details. Had a hard time but finally figured it out. I plan to post more detailed steps to help others going thru same issue.
Just recently cleaned my EGR as well due to DTC P0400. Made sure the valve functioned smoothly but not sure if smooth enough as brand new. Reinstalled and just like you said, after about 20 miles, P0400 popped back up again.
After replacing with a new one, did it fix the P0400 issue? Also, where did u buy it and how much did it cost?
I am now planning to replace it with a new one. I followed one forum post on how to remove it but it was kind of general and did not go into details. Had a hard time but finally figured it out. I plan to post more detailed steps to help others going thru same issue.
04-08-2009, 01:30 AM
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ml320
Cleaned my EGR tube also. Man, was it a pain to take out and to put back in. This fixed my P0400 DTC. Noticed tremendous improvement in power/acceleration.
However, I am now battling 2 new pending DTC's: P0170 and P0173. Have travelled 58 miles since last RESET and has not trigger the CEL light yet. Will buy a MAF Cleaner and clean the MAF sensor as suggested in other forum posts. Otherwise, will replace with a new one if the CEL lits up. Better yet, hope that the pending DTC's disappear after I clean the MAF sensor.
However, I am now battling 2 new pending DTC's: P0170 and P0173. Have travelled 58 miles since last RESET and has not trigger the CEL light yet. Will buy a MAF Cleaner and clean the MAF sensor as suggested in other forum posts. Otherwise, will replace with a new one if the CEL lits up. Better yet, hope that the pending DTC's disappear after I clean the MAF sensor.
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04-08-2009, 12:24 PM
#8
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Cleaned my EGR tube also. Man, was it a pain to take out and to put back in. This fixed my P0400 DTC. Noticed tremendous improvement in power/acceleration.
However, I am now battling 2 new pending DTC's: P0170 and P0173. Have travelled 58 miles since last RESET and has not trigger the CEL light yet. Will buy a MAF Cleaner and clean the MAF sensor as suggested in other forum posts. Otherwise, will replace with a new one if the CEL lits up. Better yet, hope that the pending DTC's disappear after I clean the MAF sensor.
However, I am now battling 2 new pending DTC's: P0170 and P0173. Have travelled 58 miles since last RESET and has not trigger the CEL light yet. Will buy a MAF Cleaner and clean the MAF sensor as suggested in other forum posts. Otherwise, will replace with a new one if the CEL lits up. Better yet, hope that the pending DTC's disappear after I clean the MAF sensor.
