99' GMC Sierra...OBDII - Code PO300

Edited: 3/12/2010 9:20:38 PM by Mater

Edited: 3/12/2010 9:16:06 PM by MaterP0300 is a random/multiple cylinder misfire code. Start with the obvious, plugs, wires, cap and rotor button. If that does not fix it go deeper. When working on cars always start with simple and move up.  There was TSB for the V6 Silverado for the A/C charge line condensing onto the cap and causing a short. Those V6's are pretty idiot proof. If you do a tune up and it doesn't fix it,  check the spider injector for weak spray on a cylinder. They are prone to failure when they get some mileage. Hope this helps. ASE Master Tech, Ford Master Tech, CAT Certified, Navistar Certified, Now Cummins Certified

i would have to say start with your 02 sensors buddies v6 did the same thing and it ended up being the two front sensors.

Edited: 3/14/2010 12:05:05 PM by POSJustin

for sure...thanks guys. ive been messin with it all weekend, doin many of the recommended things. im almost there. :) i replaced the cap, rotor, wires, gonna do some more today. the cap, rotor, and wires arent even 2 months old. luckily the wires were under warranty but it cost me 60 bucks for the cap and rotor...

yeah about 99% positive its o2 sensors but you gonna have to put it on a computer to see which o2 sensor it is cus bein a v6 it should have 3 total,one on each side of the motor before the cat and one after the cat its called bank 1 and bank 2 or you can change all 3 and that would save you trouble gettin some one with a DIAGNOSE computer cus that one little orange one from autozone dont worth a shit

Hello everybody,                            Thank you "jerry" for this information.  --------------------------------------------

yeah about 99% positive its o2 sensors but you gonna have to put it on a computer to see which o2 sensor it is cus bein a v6 it should have 3 total,one on each side of the motor before the cat and one after the cat its called bank 1 and bank 2 or you can change all 3 and that would save you trouble gettin some one with a DIAGNOSE computer cus that one little orange one from autozone dont worth a shit

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