CEL question

JameyS · **Joined:** Thu Apr 12, 2018 9:57 am **Posts:** 17

I’ve blocked off the EGR tube on both sides and currently have the MAF sensor disconnected, but I’m curious about something.
If I remove the EGR butterfly plate and plug the MAF sensor back in will it still throw a CEL?
I would think it wouldn’t be able to sense a difference in flow with the butterfly removed, but I’m not familiar with how it determines a functional EGR?
It drives great the way it is, but the CEL is always on and I’d like a heads up if it throws another CEL while I’m driving.
This is just temporary until I can afford a weeks kit and reprogram.

ebbnflow · **Posted:** Sun Apr 22, 2018 7:05 pm

EGR delete requires a tune to disable the code that gets set. You can do the DIY tune or buy from Green Diesel Engineering. You can check out the DIY tune in the CRD Tech forum.

WWDiesel · **Posted:** Sun Apr 22, 2018 9:21 pm

You can plug the MAF back in with the EGR exhaust feed tube blocked off with an EGR block off plate installed and remove the FCV butterfly plate and run with that condition until you can afford and install the Weeks elbow kit.
When you install the Weeks elbow kit, you will need to install one of the correct DIY tunes for your pectacular engine software to disable any DTC triggered codes.
I ran with this exact same condition for almost a year before the Weeks elbow kit ever came into being available... :wink:

Bottom line, get rid of the EGR and stop dumping all that soot into the intake of your engine, it is super bad for it !!! :roll:

JameyS · **Joined:** Thu Apr 12, 2018 9:57 am **Posts:** 17

WWDiesel wrote:

You can plug the MAF back in with the EGR exhaust feed tube blocked off with an EGR block off plate installed and remove the FCV butterfly plate and run with that condition until you can afford and install the Weeks elbow kit.
When you install the Weeks elbow kit, you will need to install one of the correct DIY tunes for your pectacular engine software to disable any DTC triggered codes.
I ran with this exact same condition for almost a year before the Weeks elbow kit ever came into being available... :wink:

Bottom line, get rid of the EGR and stop dumping all that soot into the intake of your engine, it is super bad for it !!! :roll:

Thanks, mostly I was just wondering if the CEL would stay lit? I don’t like the lack of gauges, and may address that in the future, but with the CEL lit all the time I have no way of telling if another issue is occurring when driving

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

JameyS wrote:

WWDiesel wrote:

You can plug the MAF back in with the EGR exhaust feed tube blocked off with an EGR block off plate installed and remove the FCV butterfly plate and run with that condition until you can afford and install the Weeks elbow kit.
When you install the Weeks elbow kit, you will need to install one of the correct DIY tunes for your pectacular engine software to disable any DTC triggered codes.
I ran with this exact same condition for almost a year before the Weeks elbow kit ever came into being available... :wink:

Bottom line, get rid of the EGR and stop dumping all that soot into the intake of your engine, it is super bad for it !!! :roll:

Thanks, mostly I was just wondering if the CEL would stay lit? I don’t like the lack of gauges, and may address that in the future, but with the CEL lit all the time I have no way of telling if another issue is occurring when driving

ISSPRO makes excellent aftermarket gauges; they specialize in high performance diesel applications.

Private message DocB and ask him how his ISSPRO gauges are holding up.

WWDiesel · **Posted:** Mon Apr 23, 2018 1:52 pm

JameyS wrote:

Thanks, mostly I was just wondering if the CEL would stay lit? I don’t like the lack of gauges, and may address that in the future, but with the CEL lit all the time I have no way of telling if another issue is occurring when driving

I did not get a DTC when operating the vehicle in this condition like you do get when operating vehicle with an unplugged MAF sensor.
I had the EGR block off plate in place, FCV butterfly plate removed, all wires still connected to the MAF, EGR & FCV, and all coolant hoses to/from the EGR cooler removed.

But I remember some on LOST in the past reported they got a DTC when simply blocking off the EGR feed tube, but I am not sure if they had removed the FCV butterfly plate or not?
I think it was a P0101 or P0401 code? Removing the FCV butterfly plate may be the key to not getting one?

Even if you do get an occasional DTC, you can always purchase an inexpensive code reader with the DTC delete function and clear any DTC's.
There are many inexpensive models available now at the Auto parts stores and online like the Innova 3020 or 3030 which allow reading and clearing of codes...

:SOMBRERO:

JameyS · **Joined:** Thu Apr 12, 2018 9:57 am **Posts:** 17

WWDiesel wrote:

JameyS wrote:

Thanks, mostly I was just wondering if the CEL would stay lit? I don’t like the lack of gauges, and may address that in the future, but with the CEL lit all the time I have no way of telling if another issue is occurring when driving

I did not get a DTC when operating the vehicle in this condition like you do get when operating vehicle with an unplugged MAF sensor.
I had the EGR block off plate in place, FCV butterfly plate removed, all wires still connected to the MAF, EGR & FCV, and all coolant hoses to/from the EGR cooler removed.

But I remember some on LOST in the past reported they got a DTC when simply blocking off the EGR feed tube, but I am not sure if they had removed the FCV butterfly plate or not?
I think it was a P0101 or P0401 code? Removing the FCV butterfly plate may be the key to not getting one?

Even if you do get an occasional DTC, you can always purchase an inexpensive code reader with the DTC delete function and clear any DTC's.
There are many inexpensive models available now at the Auto parts stores and online like the Innova 3020 or 3030 which allow reading and clearing of codes...

:SOMBRERO:

Hmmm, that’s what I was thinking. I’ll remove the FVC butterfly, reconnect the MAF when I get a chance and see what happens!

WWDiesel · **Posted:** Mon Apr 23, 2018 2:49 pm

JameyS wrote:

Hmmm, that’s what I was thinking. I’ll remove the FVC butterfly, reconnect the MAF when I get a chance and see what happens!

Any DTC due to an EGR blanked off would have to come from the MAF as it is the only flow measurement sensor on the air flow into the engine. :roll:

krb · **Posted:** Tue Apr 07, 2020 4:48 am

Appears that I am also one of the unlucky ones that gets a P0401 code with EGR blocked off and butterfly removed. I'll double check my MAF to make sure it's connected well.

How did you make out JameyS?

JameyS · **Joined:** Thu Apr 12, 2018 9:57 am **Posts:** 17

I ended up buying the tune from GDE to eliminate the CEL. It was the only way around it.

flash7210 · **Posted:** Tue Apr 07, 2020 12:36 pm

You can also use any of the DIY tunes to remove the p0401

WWDiesel · **Posted:** Tue Apr 07, 2020 2:36 pm

flash7210 wrote:

You can also use any of the DIY tunes to remove the p0401

X2

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

WWDiesel wrote:

JameyS wrote:

Hmmm, that’s what I was thinking. I’ll remove the FVC butterfly, reconnect the MAF when I get a chance and see what happens!

Any DTC due to an EGR blanked off would have to come from the MAF as it is the only flow measurement sensor on the air flow into the engine. :roll:

My GDE tune remove the MAF CEL from but not the DTC.

Check engine light and Diagnostic trouble Code are related but not the same thing !

WWDiesel · **Posted:** Tue Apr 07, 2020 11:38 pm

PZKW108 wrote:

WWDiesel wrote:

JameyS wrote:

Hmmm, that’s what I was thinking. I’ll remove the FVC butterfly, reconnect the MAF when I get a chance and see what happens!

Any DTC due to an EGR blanked off would have to come from the MAF as it is the only flow measurement sensor on the air flow into the engine. :roll:

My GDE tune remove the MAF CEL from but not the DTC.
Check engine light and Diagnostic trouble Code are related but not the same thing !

I agree, turning off or disabling a CEL for a specific OBD code is possible in the software coding.
DTC (Diagnostic Trouble Code) & "Check Engine Light" are related.
The Check Engine Light will not be triggered unless there is one or more accompanying or related DTC's identified by the OBD monitoring system that triggered it.
You can have a stored or pending DTC and not have a CEL, but you won't have a CEL without an active DTC.

There are two types of OBD II diagnostic trouble codes: generic “P0” codes and enhanced “P1” codes.
All vehicles use the same basic definitions for the "P0" generic codes, but the enhanced codes are vehicle-specific designated by the vehicle's manufacturer and can vary from vehicle to vehicle.

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

Very well explained WW :wink:

My66dodge · **Posted:** Wed Apr 08, 2020 9:21 pm

The only thing that will turn on the check engine light is emissions related items, all other events will set a code but not turn on the light. That’s why on a regular basis at my shop someone will come in and say the cel just came on but have MANY codes stored from prior.

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WWDiesel · **Posted:** Wed Apr 08, 2020 11:17 pm

My66dodge wrote:

The only thing that will turn on the check engine light is emissions related items, all other events will set a code but not turn on the light. That’s why on a regular basis at my shop someone will come in and say the cel just came on but have MANY codes stored from prior.

I thought there were some non-emission DTC's like security faults that would still illuminate a MIL?

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

WWDiesel wrote:

My66dodge wrote:

The only thing that will turn on the check engine light is emissions related items, all other events will set a code but not turn on the light. That’s why on a regular basis at my shop someone will come in and say the cel just came on but have MANY codes stored from prior.

I thought there were some non-emission DTC's like security faults that would still illuminate a MIL?

I think 66 is right as every engine management dtc are somehow emission related.

You won't get cel from body control module and ABS , SRS got their own lights !

It was true for sure when obdII started anyway !

My66dodge · **Posted:** Thu Apr 09, 2020 4:23 pm

Government mandate

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layback40 · **Posted:** Thu Apr 09, 2020 5:25 pm

WWDiesel wrote:

My66dodge wrote:

The only thing that will turn on the check engine light is emissions related items, all other events will set a code but not turn on the light. That’s why on a regular basis at my shop someone will come in and say the cel just came on but have MANY codes stored from prior.

I thought there were some non-emission DTC's like security faults that would still illuminate a MIL?

I agree WW ! There are plenty of codes that are not emission related that will cause the check engine light. Start with transmission codes.

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