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Discussion Starter #1
This morning, as I was on my commute to work, the CEL came up, minutes later, a warning with "Engine Power Reduced" displayed. Driving for another 15 miles, the warning went away, but CEL was still there. 20 minutes after, that same warning came up again as I was slowing down on a traffic light.

When got to the parking lot, I checked the code and the reader said it's P00B7. Cleared the code. Will see if it comes back this afternoon.

Did some research, it's the Low Flow Coolant. Further digging around, it could be an issue with EGR. At 43K miles? Wow...

Anyway, called dealer to bring it in. Could not make any appointment yet.

I know some of you had mentioned about the same problem, same code. And EGR was mentioned in the message. What actually went wrong on yours?
 

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What does your coolant level look like? These trucks are known to consume coolant via the EGR. I've had to add coolant to mine already and it has only been 30K miles.
 

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Discussion Starter #3
I checked on the feed tank and it showed about an inch above the Min level. However, I open the radiator cap , there was nothing in there. I filled it up last night. So far, I have not seen the CEL comes on again yet. Hope that was the problem, low on coolant.

Thanks,
 

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This morning, as I was on my commute to work, the CEL came up, minutes later, a warning with "Engine Power Reduced" displayed. Driving for another 15 miles, the warning went away, but CEL was still there. 20 minutes after, that same warning came up again as I was slowing down on a traffic light.

When got to the parking lot, I checked the code and the reader said it's P00B7. Cleared the code. Will see if it comes back this afternoon.

Did some research, it's the Low Flow Coolant. Further digging around, it could be an issue with EGR. At 43K miles? Wow...

Anyway, called dealer to bring it in. Could not make any appointment yet.

I know some of you had mentioned about the same problem, same code. And EGR was mentioned in the message. What actually went wrong on yours?
HI,
As you know,, recommended Coolant change is required at 45K or 36 months.. Level in the Recovery Bottle should be when cold with outside temps being in the 60's at the half way or mid line where the Seam Lip is of the Bottle.. now it may be above or below it, but not much over 1/2 above or below that seam line.. of the bottle..

DTC CONSULT
(Trouble diagnosis content) DTC detection condition
P00B7
ENGINE COOLANT FLOW
(Coolant level - data valid but below normal operating range - moderately severe level)
1 Diagnosis condition Continuously when key is ON, or engine is running
Signal (terminal) — Threshold Coolant level sensor voltage:• >≥ 3.00 V
Diagnosis delay time Diagnostic runs continuously when the engine is running
POSSIBLE CAUSE
• Low coolant level
• Coolant level sensor
• Harness and connectors
The coolant level sensor is a switch and is used to measure the level of the engine coolant in the radiator top
tank. The coolant level sensor is immersed in the coolant and returns a different signal voltage when
immersed in coolant verses being out of coolant. The Engine Control Module (ECM) monitors the change in
the signal voltage to determine the level of the engine coolant.
 

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What does your coolant level look like? These trucks are known to consume coolant via the EGR. I've had to add coolant to mine already and it has only been 30K miles.
EHIDE...I have a theory I'm kicking around in my head on premature EGR Cooler failure and coolant loss. Especially in the 30-50k range.
Would you happen to have tested your coolant when adding with test strips? If not...do you have a digital multimeter and would you be willing to be a "easy test guinea pig"?
 

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Not Sure about using the MM... maybe this would be interesting: Knowledge.. ??
https://app.box.com/s/mc3kaetdmj38ebzomyscxe9wt8rvotdg Why MM not.
Now I'm not an authority on anything... All I have ever seen and I have not seen it all.. is below from the Cummins side that I'm aware of: The way to decide on coolant change intervals can include:
- Coolant test strips check coolant pH / acid levels (corrosion risk)
- Owner’s manual service intervals
- Coolant maker’s change intervals
- Distance and time
To be safe, you can use a coolant change interval that is “de-rated”, like 25% less then the time recommended. This is because corrosion and aging of coolant is a 24 hour a day thing, even when the vehicle is parked. Corrosion damage to heater core, rad and head gaskets is cumulative and permanent.
Coolant appearance is NOT a good indicator. Few modern vehicles will ever have coolant that looks “dirty” unlike the old days.
As we know Fleetwood part of the Cummin's line.. offers some easy means for testing of Coolant for your Diesel.. see Below

https://www.cumminsfiltration.com/sites/default/files/LT15068.pdf

Now as far as the EGR and what's happening with loss of Coolant.. I wonder about the O'ring tube and Gasket associated with the components associated in that area.. There are more than half dozen O-rings and Gaskets in that area alone and under pressure, engine vibrations etc.. and being hidden and because where some are located you could be loosing and never know it during the normal operation of the engine..
I know I didn't solver anything here, but somethings to consider..

Enjoy, Be Safe and Keep Burning Diesel
Ric

Enjoy
 

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EHIDE...I have a theory I'm kicking around in my head on premature EGR Cooler failure and coolant loss. Especially in the 30-50k range.
Would you happen to have tested your coolant when adding with test strips? If not...do you have a digital multimeter and would you be willing to be a "easy test guinea pig"?
Sure.. what would you like me to do? Conductivity test?
 

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EHIDE...I have a theory I'm kicking around in my head on premature EGR Cooler failure and coolant loss. Especially in the 30-50k range.
Would you happen to have tested your coolant when adding with test strips? If not...do you have a digital multimeter and would you be willing to be a "easy test guinea pig"?
Sure.. what would you like me to do? Conductivity test?
Yes sir please on VDC and looking for anything above .2 VDC.
I might be crazy but I'll explain why and this might should have clicked in my head earlier.
What we learned with EGR cooler failures on the 6.0 was they were directly related to high acidity in the coolant.
We were seeing small numbers of failures early on between 30 and 50k.
We assumed poor initial coolant quality....we were wrong.
Electrical grounds not being tight or connected from the factory were causing the failure...and as I know you know electrolysis combined with dissimilar metals in our engine bay can accelerate very very quickly.
I believe I've read just about as many posts on grounds being loose or wires not being connected from the factory on the XD as I have EGR Cooler failure.
...wondering if there is a connection.....
 

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Yes sir please on VDC and looking for anything above .2 VDC.
I might be crazy but I'll explain why and this might should have clicked in my head earlier.
What we learned with EGR failures on the 6.0 was they were directly related to high acidity in the coolant.
We were seeing small numbers of failures early on between 30 and 50k.
We assumed poor initial coolant quality....we were wrong.
Electrical grounds not being tight or connected from the factory were causing the failure...and as I know you know electrolysis combined with dissimilar metals in our engine bay can accelerate very very quickly.
I believe I've read just about as many posts on grounds being loose or wires not being connected from the factory on the XD as I have EGR Cooler failure.
...wondering if there is a connection.....
I need a little more detail about what you're looking for. For a coolant conductivity test, I would build a volumetric fixture with known dimensions (and cross sectional area) and apply a uniform electric field from one end of the fixture to the other and measure current flow through the sample, sweeping the voltage looking for nonlinearily.

Where are you asking for a voltage reading, and is it relative to vehicle ground?
 

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Yes sir please on VDC and looking for anything above .2 VDC.
I might be crazy but I'll explain why and this might should have clicked in my head earlier.
What we learned with EGR failures on the 6.0 was they were directly related to high acidity in the coolant.
We were seeing small numbers of failures early on between 30 and 50k.
We assumed poor initial coolant quality....we were wrong.
Electrical grounds not being tight or connected from the factory were causing the failure...and as I know you know electrolysis combined with dissimilar metals in our engine bay can accelerate very very quickly.
I believe I've read just about as many posts on grounds being loose or wires not being connected from the factory on the XD as I have EGR Cooler failure.
...wondering if there is a connection.....
I need a little more detail about what you're looking for. For a coolant conductivity test, I would build a volumetric fixture with known dimensions (and cross sectional area) and apply a uniform electric field from one end of the fixture to the other and measure current flow through the sample, sweeping the voltage looking for nonlinearily.

Where are you asking for a voltage reading, and is it relative to vehicle ground?
Sorry... should have explained.
1. Set multimeter to VDC.
2. Place red probe tip into coolant level. Probably easier done at radiator cap vice tank.
3. Connect black probe to battery ground.
View results..hopefully we see no reading but if we see something like a .2 VDC or above there is a problem.
What we're looking for is high acidity and electrolysis in the coolant.
 

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Arice, is correct on Voltage and Grounds and possible connection to Premature failures of the EGR system.. conductivity is no doubt a possible situation.. What your looking for is a voltage reading if above 0.3-0.4 volts of the coolant... however there are opinions on this.. Might I suggest Online do a search to give you an Idea best way to check what Arice is suggesting..

Here is Only One of Many Links to the Topic
https://www.familyhandyman.com/auto...e/coolant-testing-with-a-multimeter/view-all/

You can use a search like this in Google -" Checking Diesel coolant for dielectric voltage "

Enjoy Be Safe..

Ric
 

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Not Sure about using the MM... maybe this would be interesting: Knowledge.. ??
https://app.box.com/s/mc3kaetdmj38ebzomyscxe9wt8rvotdg Why MM not.
Now I'm not an authority on anything... All I have ever seen and I have not seen it all.. is below from the Cummins side that I'm aware of: The way to decide on coolant change intervals can include:
- Coolant test strips check coolant pH / acid levels (corrosion risk)
- Owner’s manual service intervals
- Coolant maker’s change intervals
- Distance and time
To be safe, you can use a coolant change interval that is “de-rated”, like 25% less then the time recommended. This is because corrosion and aging of coolant is a 24 hour a day thing, even when the vehicle is parked. Corrosion damage to heater core, rad and head gaskets is cumulative and permanent.
Coolant appearance is NOT a good indicator. Few modern vehicles will ever have coolant that looks “dirty” unlike the old days.
As we know Fleetwood part of the Cummin's line.. offers some easy means for testing of Coolant for your Diesel.. see Below

https://www.cumminsfiltration.com/sites/default/files/LT15068.pdf

Now as far as the EGR and what's happening with loss of Coolant.. I wonder about the O'ring tube and Gasket associated with the components associated in that area.. There are more than half dozen O-rings and Gaskets in that area alone and under pressure, engine vibrations etc.. and being hidden and because where some are located you could be loosing and never know it during the normal operation of the engine..
I know I didn't solver anything here, but somethings to consider..

Enjoy, Be Safe and Keep Burning Diesel
Ric

Enjoy
Hi Ric,one of the old school ways to do a "down and dirty"quick check for electrolysis in the cooling system is to use a MM. If acid levels are extremely high and electrolysis present it will register on a MM.
I also read the doc and link....problem with those guys is they were all over the board with their tests ..why they started with an analog meter I don't know...other than it shows a lack of understanding of meters and voltage.
Now ..this test with a digital MM is not meant to be an exact science or tell you when to change coolant..it's a down and dirty test to quickly check for high acidity and electroysis which generates voltage...a sound cooling system won't..
Every time I have used this test method..and VDC was present on the meter, and then cross checked with a coolant sample, the meter was right...everytime.
I guess those guys would also say we can't light a light bulb with oranges either,??
 

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Took my titan into the dealer, ran tests, they filled the radiator up as it was low and cleared the codes drove home and no CEL. we will see if it comes on in the morning on my way to work.
 

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Sorry... should have explained.
1. Set multimeter to VDC.
2. Place red probe tip into coolant level. Probably easier done at radiator cap vice tank.
3. Connect black probe to battery ground.
View results..hopefully we see no reading but if we see something like a .2 VDC or above there is a problem.
What we're looking for is high acidity and electrolysis in the coolant.
Ok so you are looking for conductivity in the coolant :wink2:

The unfortunate thing is that it won't tell you anything about why it's conductive. But, I'll try to put together a fixture this weekend and see what comes up.
 

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Premium Member
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1,094 Posts
Sorry... should have explained.
1. Set multimeter to VDC.
2. Place red probe tip into coolant level. Probably easier done at radiator cap vice tank.
3. Connect black probe to battery ground.
View results..hopefully we see no reading but if we see something like a .2 VDC or above there is a problem.
What we're looking for is high acidity and electrolysis in the coolant.
Ok so you are looking for conductivity in the coolant /forum/images/CumminsTitan/smilies/tango_face_wink.png

The unfortunate thing is that it won't tell you anything about why it's conductive. But, I'll try to put together a fixture this weekend and see what comes up.
You are absolutely right in that it won't. It's just a starting and reference point.
We also used to use this as a quick tool for when heater cores failed. Was it just a bad core or did electroysis in the coolant kill it?
If so, we knew to also further test, flush, and replace the coolant and start chasing down the source vice simply replacing the heater core to see it fail again.
Test strips could do the same thing but every techs tool chest doesn't have them but they do have a multimeter... and when you're in the field working doesn't often allow for readily available coolant test kits.
Curious to see if I'm crazy or not and how the Nissan coolant reacts as I'm not entirely familiar with the Nissan "blue" chemistry.
 

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You are absolutely right in that it won't. It's just a starting and reference point.
We also used to use this as a quick tool for when heater cores failed. Was it just a bad core or did electroysis in the coolant kill it?
If so, we knew to also further test, flush, and replace the coolant and start chasing down the source vice simply replacing the heater core to see it fail again.
Test strips could do the same thing but every techs tool chest doesn't have them but they do have a multimeter... and when you're in the field working doesn't often allow for readily available coolant test kits.
Curious to see if I'm crazy or not and how the Nissan coolant reacts as I'm not entirely familiar with the Nissan "blue" chemistry.
Fair enough...

Usually the only difference between the various colors of antifreeze/coolant is the inhibitor mix. There are so many different colors now, too...
 

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Premium Member
Joined
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1,094 Posts
You are absolutely right in that it won't. It's just a starting and reference point.
We also used to use this as a quick tool for when heater cores failed. Was it just a bad core or did electroysis in the coolant kill it?
If so, we knew to also further test, flush, and replace the coolant and start chasing down the source vice simply replacing the heater core to see it fail again.
Test strips could do the same thing but every techs tool chest doesn't have them but they do have a multimeter... and when you're in the field working doesn't often allow for readily available coolant test kits.
Curious to see if I'm crazy or not and how the Nissan coolant reacts as I'm not entirely familiar with the Nissan "blue" chemistry.
Fair enough...

Usually the only difference between the various colors of antifreeze/coolant is the inhibitor mix. There are so many different colors now, too...
Started my own test this evening.
.14 VDC in cooling system (engine off); .17 VDC (engine running; accessories on). Pics attached.
Wife wants Christmas lights down....more to follow.
 

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This morning, as I was on my commute to work, the CEL came up, minutes later, a warning with "Engine Power Reduced" displayed. Driving for another 15 miles, the warning went away, but CEL was still there. 20 minutes after, that same warning came up again as I was slowing down on a traffic light.

When got to the parking lot, I checked the code and the reader said it's P00B7. Cleared the code. Will see if it comes back this afternoon.

Did some research, it's the Low Flow Coolant. Further digging around, it could be an issue with EGR. At 43K miles? Wow...

Anyway, called dealer to bring it in. Could not make any appointment yet.

I know some of you had mentioned about the same problem, same code. And EGR was mentioned in the message. What actually went wrong on yours?
just the coolant reservoir sensor - that was it. Simple. It happened about a week after I did a preventative coolant flush so wondering if that caused it.
 
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