CP4 Reliability Poll - Chevy and GMC Duramax Diesel Forum
11-16 LML Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

View Poll Results: Has your LML experienced a complete CP4 failure?
Yes < 25k miles 7 1.04%
No < 25k miles 192 28.44%
Yes 25k - 100k miles 31 4.59%
No 25k - 100k miles 297 44.00%
Yes > 100k miles 21 3.11%
No > 100k miles 127 18.81%
Voters: 675. You may not vote on this poll

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post #1 of 600 (permalink) Old 10-04-2014, 10:15 PM Thread Starter
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CP4 Reliability Poll

Like many of you, I've become quite concerned with the reliability of the CP4 in our trucks. This thread is an effort to condense the numerous CP4 failure/success posts into one format that shows hard data. Please select one of the appropriate responses listed for your OWN vehicle only! By doing so, we can ensure more accurate data as I believe the DF represents a good cross-section of the LML population.

Looking for the following info:

Mileage at time of failure
Engine Hours if known
Tuned Y/N
Lift pump Y/N (which brand?)
Lube added Y/N (If so, how frequently)
Fixed under warranty Y/N
External cause of failure (such as bad fuel)

2012 GMC Sierra CCSB 4x4 - SOLD
2019 Chevy Silverado CCSB 4x4
1997 Toyota Land Cruiser

Last edited by uscmas412; 02-26-2015 at 07:46 PM. Reason: updates
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post #2 of 600 (permalink) Old 10-07-2014, 01:50 AM Thread Starter
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If you've had a failure, please list the mileage the CP4 malfunctioned and whether or not your truck was tuned. I'm hoping we get at least 75-100 votes in the poll!

2012 GMC Sierra CCSB 4x4 - SOLD
2019 Chevy Silverado CCSB 4x4
1997 Toyota Land Cruiser
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post #3 of 600 (permalink) Old 10-08-2014, 01:08 AM
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2 out of 42 huh, yes mine was one of the two, 76K miles, tuned since 9K. Insurance man came look at the pump when I got it out and the screen in the injector rail and said he thinks water had something to do with it. All the horror stories you hear I was waiting for a lot higher number. The way he talks he hardly ever looks at a gm, says even if they suspect water the usually just warranty them unless its over on mileage or tuned (mine was both). Says he looks at fords all the time with the same pump failure, cause they wont warranty them if they even find a hint of water.
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post #4 of 600 (permalink) Old 10-08-2014, 04:27 AM
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May be a dumb question but are you referring to your auto insurance? I've called several insurance companies to ask about the "what if" questions such as a pump failure and everyone says it would not be covered under insurance.
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post #5 of 600 (permalink) Old 10-08-2014, 04:43 AM
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Yes sir auto insurance, most insurance companies have a special department for diesel engines. If you have an engine failure and call them they will go to the mechanic and take samples from the tank, take the filter, inspect the pump since mine was out, and he pulled a fuel rail screen/sensor thing. If they conclude it was a cause of contaminated fuel (aka water in the fuel) it will be covered under the comprehensive policy. I didn't know about it till someone at work told me. I called and they sure come to the house look at it. I don't know yeat what the decision is but I'm glad they at least come look at it.
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post #6 of 600 (permalink) Old 10-08-2014, 08:41 PM
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Quote:
Originally Posted by uscmas412 View Post
Like many of you, I've become quite concerned with the reliability of the CP4 in our trucks. This thread is an effort to condense the numerous CP4 failure/success posts into one format that shows hard data. Please select one of the appropriate responses listed for your OWN vehicle only! By doing so, we can ensure more accurate data as I believe the DF represents a good cross-section of the LML population.

If you have experienced a failure, list the mileage and any external factors that may have induced the malfunction. While this poll may not be statistically sound, it should give us a general idea of the failure rate in LML's.
Mine went out at 109,000 completely stock, dealership for almost every issue. I spend 95% of my time in Florida. It seems that a lot of Canadian folks have fuels with lubricating additives at their fuel stations more than here in the states and I think thats why the US experiences many more failures.
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South Florida GMC
2011 GMC LML CCLB SLT DRW 4x4
285/75/R17 B & W turnover ball
Antitheft hose clamp installed on tailgate hinge
109,000 first cp4 replaced along with most of fuel system Airdog 165 added + Stanadyne Summer Formula
GM DRW Member #256
"The NOx Sensor is on the way out when you drive it out of the lot"
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post #7 of 600 (permalink) Old 10-10-2014, 06:21 AM
 
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Only 60 responses so far and three (5%) indicate failures. Hope more will participate in the poll.

2011 Silverado LML 4x4 LTZ Z71
Stock w/Edge Insight CS
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post #8 of 600 (permalink) Old 10-10-2014, 08:23 PM
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Quote:
Originally Posted by frajit View Post
Only 60 responses so far and three (5%) indicate failures. Hope more will participate in the poll.
There is a bunch of different threads about this same thing. I must have read hundreds of cp4 failures. I just dont think people are actually voting
Hope it gets better

South Florida GMC
2011 GMC LML CCLB SLT DRW 4x4
285/75/R17 B & W turnover ball
Antitheft hose clamp installed on tailgate hinge
109,000 first cp4 replaced along with most of fuel system Airdog 165 added + Stanadyne Summer Formula
GM DRW Member #256
"The NOx Sensor is on the way out when you drive it out of the lot"
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post #9 of 600 (permalink) Old 10-10-2014, 08:56 PM
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Mine has just under 2000 miles, no pump failure yet. Would not expect it at this point. I voted, but if something changes will post here on this thread.

Maybe should have a minimal mileage requirement to vote.

2015 LML - Stock Turbo and Injectors, Built Tranny, Sportsman CP3
Dyno'd 2/6/16: 569 RWHP/1149 RWTQ
Best 1/8 mile: 8.20 sec
Best 1/4 mile: 12.98 sec

07.5 LMM (Previous truck)
Dyno'd 4/13/13: 643 RWHP/1086 RWTQ

Thanks to A-Star Diesel Performance (George Loewen)
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post #10 of 600 (permalink) Old 10-10-2014, 09:17 PM
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Mine failed at 28k miles. Completely stock.

2012 Black 2500 HD Crew Cab Z71 LT LML
Factory 20's Terra Grappler G2's 275/65/20
Bully Bars (black)
Tinted Windows
Backflip Bed Cover
Cognito Leveling Kit
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