P1406 and Occasional P0308

Posts : 212 Join date : 2012-07-16 Location : Maine

So on my 96 K1500 (with a 305) I have had a consistent P1406 code, indicating issue carbon blockage in the pintle of the EGR valve. Its been happening for the last couple of months. In the same time period I get an occasional misfire on cylinder 8 (p0308) that accompanies some stumbling and rough idle. That happens only when the engine is cold, but as it has warmed some it has not happened as much. I did the plugs and wires a month ago to see if that would fix the misfire. Plugs were toast but still did not fix the misfire.

Anyway I have not had the misfire in a week but I decided to tackle the EGR. So I pulled the valve and it looks fairly new and there was little carbon buildup, either by the pintle or the port to the intake. I cleaned it anyway and threw it back on with a new gasket. Code pops up again after a minute of driving around.

So it might be a stupid question as the next obvious step is to replace the EGR valve, but as they are around $120, I wanted to see if the issue was elsewhere before I throw money at it. I am kind of a dummy at this so should I look for issues with the MAF? Exhaust? Intake? I realize those might be more effort and $$$ but just want to know if there is the potential for it being something other than the EGR, especially with the recent misfire issues.

Posts : 4294 Join date : 2009-12-16

This may be a dumb thought, but did you disconnect the battery long enough for the codes to go away? If not, and you have a stored code, it will pop up until the computer relearned it's no longer an issue. Could be wrong.

Posts : 212 Join date : 2012-07-16 Location : Maine

I cleared the code first so I figured that would take care of it.

Subject: Re: P1406 and Occasional P0308 Sun Mar 08, 2015 9:11 am

Take the EGR off the engine and plug up the intake holes, start the engine and watch the EGR (still plugged into the harness) if it doesn't move the EGR is junk.

When you cleaned the valve did you stick anything down into the intake holes to clean them too?

Posts : 212 Join date : 2012-07-16 Location : Maine

Ironfistdog wrote:: Take the EGR off the engine and plug up the intake holes, start the engine and watch the EGR (still plugged into the harness) if it doesn't move the EGR is junk.

When you cleaned the valve did you stick anything down into the intake holes to clean them too?

Thanks for the tip and yeah the pintle barely budges so it's junk. Oh well. Still have not had the misfire in some time so hopefully this will remove all the gremlins for now.