• Tiny
  • Anonymous
  • 2004 Chevrolet Trailblazer
  • 140,000 miles

Engine is running rough. Did diagnostic and got the following codes. 301, 172, 485, 420 442, 526. 301 indicates cylinder 1 misfire. Have changed coils and plugs. Problem still exists. Any ideas? Is the cylinder 1 misfire causing the other codes?

Tuesday, November 27th, 2012 AT 3:25 PM

1 Reply

  • Tiny
  • racefan966
  • Expert
  • 5,136 posts

Ok so you have P0172 which means it is running rich, then you have P0420 which is cat insuffient flow (this can cause a miss), P0442 is EVAP system leak, this could be anything from a bad gas cap to something wrong with the evap system, and P0526 has to do with the coolant fan speed problem. As for 485 I find no such code if it is 483 then again coolant fan system problems. Now the missing may be either an injector or something to do with the cat or one of the O2's and or the evap problem. So if you have a digital ohm meter ohm the number 1 injector and get back to me with the reading and we will go from there ok.

Was this
Tuesday, November 27th, 2012 AT 4:10 PM

Please login or register to post a reply.

Similar Questions