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8.1 Crankshaft Position Sensor

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#1 tjg79



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Posted 05 September 2009 - 12:31 AM

Scan code indicates a problem with the crankshaft position sensor. I've had two incidents of cranks but fails to start after a short trip, but started ok several hours later.

Is the crankshaft position sensor reasonably easy to replace? Dealer wants $400.00 for the task. I can get the sensor for $62 (shipping included) from GMPartsDirect.

I don't have my GM shop manuals with me at the moment, so any advice from someone who's been there, done that would be appreciated.

Regards to all.
2001 GMC Yukon XL 2500HD 4x4 V8-6.0
2002 GMC Sierra Crew Cab 2500HD 4x4 V8-8.1/Allison

#2 die hard

die hard


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Posted 05 September 2009 - 08:22 AM

very easy to replace 1 bolt [10mm head size [ and 1 plug is located on the back side of engine betwen the bell hosing and valve cover .. i change mine from underneath truck ..... bolt hole and plug are kinda in the way of each other but the new one has been change and goes in easyer ..may take a little force to remove ...

#3 die hard

die hard


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Posted 05 September 2009 - 08:25 AM

you may need to clear your codes when finisded cost about 90 bucks for the sensor

#4 Haulin' 8.1

Haulin' 8.1


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Posted 05 September 2009 - 08:37 AM


2001 Siverado HD 2500 SBCC in Black
GM Vortec 8100, Allison, 3.73, 4X4
Mods: Goodmark SS cowl hood, Ranch Hand bumpers, black toolbox, custom bed cover, full tint, Volant with home made ram air, BBK 80mm TB, Granetelli MAF, Marine Injectors, Hypertech, Champion RS12YC plugs, Magnaflow 3" dual in X-path dual out muffler and tail pipes, Fuzion XTi 265's, Velvet Rides, Pioneer 10" subs, amps, you know the usual stuff.
Coming soon: 4.56 gears, Autorotor supercharger by Whipple with Duramax intercooler, and GM HP3 cylinder heads.
If you've modded your 8.1's timing and run hard try Champion RS12YC plugs gapped at 0.055". Less knock, more power. Yes you have to change them more often (25K), but this is a performance mod. Besides they're cheap and easy to do.

Yea though I drive the the valley of the shadow of Diesel,
I will fear no turbo;
For your horsepower art with me;
Your bore and stroke, they comfort me.

#5 tjg79



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Posted 06 September 2009 - 02:12 PM

Thanks guys. It appears to be a no brainer decision between DIY or Dealer.

Does anyone know if a Genisys EVO is capable of performing the Crankshaft Position Variation Learn Procedure after replacing the crank sensor?

I've been watching eBay for a resonably priced Tech II, but I've had no luck yet.

Other than flash reload/upgrade modual memory, what can the Tech II do that the Genisys EVO can't?

Thanks again.
2001 GMC Yukon XL 2500HD 4x4 V8-6.0
2002 GMC Sierra Crew Cab 2500HD 4x4 V8-8.1/Allison

#6 Greg75



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Posted 08 September 2012 - 12:52 AM

It does have the special test capability of doing so. Many times it would also depend on the vehicle, but for example, I look up a 2006 Chevy Silverado with 6.0L, and yes it does the relearn.
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#7 Sierra35008.1


    GM Til the end "

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Posted 08 September 2012 - 01:29 PM

I would check around..when i asked my local gmc dealer it was $247 parts&labor..
I guy i know that has a cpl 8.1 trucks says he had one went around 75,000 miles, and when he changed it the truck felt 100% better.
Im pretty sure the 01-03/4 8.1,s were easier to do the 04.5/07

2005 gmc sierra 3500 ext cab long box 8.1,allison,11.5 ring gear, 4x4, 4:10,s, S&B intake,BlackBear Tune, Raylar Cam,
Stainless works long tubes on there way,.. blocks in rear, new keys up front, mickey thompson classic II,s, 305-70-16 firece attitude M/T
Rancho shocks, No Cats, stainless X-pipe,maganflow 3" straight thru mufflers, Back rack,
" Still under construction"

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