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Uh Oh Code 8 4


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started my truck after 5 min of idle it was about 40 degrees f i hit the cruse to idle it up by the time it got to 800 rpm check engine lite came on imeditly turned off cruse and checked code 8 4 called dealer, was told injector pump no. 4 cyl. also said it could be a fluke, i shut down restarted and it was still there. after about 2 min. it went off havent seen it since. do you think run it or go ahead and put ip. in. im getting ready to head out west for a week or two and im not real keen on the guy's out west working on a mack.

so what do ya think!

i never had an ip go out can i limp in like that or is it something that has to be replaced immediatly

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EUP pump codes are normal on 04 and up EGR engines, the extrem heat around the EUP's cause them to start to code sooner than they should. If the FMI of the code is 8 (abnormal frequency responce)I would drive it as this seems to be a common thing when cold . If it was mine I wouldn't change it till the code started coming active when the truck is hot. It might go a year or more with out failing. But some guys get nervous when that malfunction light is on and want to change it. We see trucks come in all the time with black tape over the EML (electronic malfunction light).

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that makes sence drive it till it throws that code at operating temp. have put 1500 miles on it since and havent seen it again

thanks for your time

If you ever get more than 1 or 2 active (8-1 through 8-6) at the same time, have your fuel pressure checked and it could be low and will set off several EUP codes at once. Those fuel supply pump have been known to go bad (plastic gear slips on steel shaft)

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