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-   Duramax Second Generation: 2004.5-2005 (LLY) (https://www.dieselplace.com/forum/63-gm-diesel-engines/40-duramax-second-generation-2004-5-2005-lly/)
-   -   Question: Bad injector causing limp mode? (https://www.dieselplace.com/forum/63-gm-diesel-engines/40-duramax-second-generation-2004-5-2005-lly/977922-bad-injector-causing-limp-mode.html)

Happywatcher 08-12-2019 11:18 PM

Bad injector causing limp mode?
04 2500 4X4 lly 300,000 mi.
Sets codes p0201,204,206,207,& 2146. Just one or any combo of the four. Clear codes restart & instantly sets a code(s) or drives fine from 5 to 500 mi.
The #2 & #7 harness update done, no harness chafe problem. All plugs ice picked. Still goes limp. Balance rates are good except #7 starts at -5.5 & will slowly go up to -6.2. Does that indicate a bad injector or something else? And can that cause the limp mode. Or is a bad ecu, ficm ? Cracked solder joints? Please help!

OkDually 08-12-2019 11:36 PM

Thread relocated over to "Duramax Second Generation: 2004.5-2005 (LLY)" for appropriate responses


Rvn4me 08-13-2019 09:21 AM

Your signature says 04 so are you posting in the wrong generation? Do you have a LB7 or LLY
It is very rare for a FICM to go bad on a LLY engine LB7 yes -- shorted wires on the FICM bracket-very common.
When a fuel injector circuit condition is detected by the FICM, all of the fuel injectors on the affected ignition voltage circuit will be disabled.
If a circuit condition is detected on a fuel injector circuit for cylinders 1, 4, 6, or 7, DTCs P0201, P0204, P0206, or P0207 will set, along with DTC P2146.


Proper way to check balance rates

Bad injector won’t cause limp mode but P2146 will

Happywatcher 08-13-2019 12:25 PM

Okay thanks for the reply. I don't always get the 2146, & the p020_ # never comes up the same, it sets anyone of the four or a combo of any or all four with or without the 2146. I don't think it has set the 2146 by it self. Sometimes it affects the fuel gauge to empty & turns low fuel light on. I've seen other posts with the same problem but haven't found one with the solution. The part I don't understand is that it will set the code (s) instantly like a hard code when starting after a reset but never the same cylinder in the freezer frame. or it could run fine for days, I'm a retired ASE master tech but I put in most of my time on the line working for Honda and they didn't have any diesels. I know control units don't go bad very often (unless they're known to) even then, which one? Since the ECU is actually the one that pulses the ground to the injector, correct?
Help me please!

Happywatcher 08-13-2019 04:01 PM

Sorry, I'm new, didn't mean to put it in the wrong place. It's a 04 GMC 2500hd 4X4 with the lly engine. Thanks for the link to the balance rate quarrel. I'll look into that a bit more. But graduated cylinder is the only way to really be sure & allows you to visually see the spray, right? I'm diesel ignorant, but I can usually repair anything with the proper info.

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