2006 chevy express 6.0 codes
 

I have a cheap code reader that I was able to pull the codes from my van. Check engine light will come on after about 200 miles of driving. mostly it is 171 & 174 but will also throw 300 every so often. It has a noticeable miss when in gear sitting still. I am not at all familiar with the 6.0 platform. From what I read the 171 &174 are a lean condition and 300 is a random misfire. Where should I start looking or since I know nothing about them would I be wiser to take it to a shop or dealer? I don't want to start just throwing parts at it if I can help it.

I am also having issue with the emergency brake not taking up. One of the cables was broke so I went ahead and bought all new cables as well as the foot pedal control since they were reasonably priced. I can get it to snug up enough I can't turn by hand but once on the ground it is like it is still not on. I don't see any way of adjustment.

Thanks in advance
Richard

Re: 2006 chevy express 6.0 codes
 

P171 and p174 are lean codes
P300 is misfire
Either take it to a mechanic or try fixing yourself lean out to much will kill your motor

https://www.700r4transmissionhq.com/...chevy-express/

Re: 2006 chevy express 6.0 codes
 

How many miles on it? Could be due for a tune up. Lean codes could also be from a vac leak at the booster, or an exhaust leak. I'd check for exhaust leaks first.

Re: 2006 chevy express 6.0 codes
 

Thanks for that link

has roughly 179k on it. I just bought this van for work and it had busted manifold bolts and a busted manifold that the place I bought it from fixed, so there are supposed to be no leaks now. I don't know any history on the motor so i guess my best bet is taking it to someone at this point. Since I lost my hearing several years back it would be impossible for me to listen for any kind of leaks.

Re: 2006 chevy express 6.0 codes
 

.

Misfire code have an associated cylinder? If so, swap a coil pack or plug around see if code moves with coil pack or plug.

...

Hth,

-klb

Re: 2006 chevy express 6.0 codes
 

I have cleared the codes a couple times. I bought some MAF cleaner and spray cleaned that as directed on the can and thought that fixed it but after about 250 miles or so the light came back on. before that it seemed like I did not get much over 100 before it came on. The random misfire code only popped up once or twice and has not since I cleaned the MAF sensor. The motor still has a noticeable stumble while idling in gear at a stop light or such.

Re: 2006 chevy express 6.0 codes
 

I would start with spark plugs...if the engine has Displacement on Demand (DOD) the plugs often get fouled and will set P0300
NGK TR55 are what I typically put in stock engines

lean codes could be:
vac leak
the tune is screwed up if someone messed with the stock tune
1 or more injectors not working

If an injector or 2 are not working, that could set both your codes...lean and will show misfire.

Re: 2006 chevy express 6.0 codes
 

when i see the lean codes with a p0300 normally need intake gaskets

Re: 2006 chevy express 6.0 codes
 

I stopped and got plugs and wires tonight and will put them on in the morning. It has several mismatched wires so lord only knows what the po has done. I have read elsewhere about the intake gasket being a likely target as well. One thing I noticed today was that the only time the check engine light comes on is when I fill up with gas or if I get below 1/4 tank on gauge. Hope to know more tomorrow

Re: 2006 chevy express 6.0 codes
 

I put plugs and wires on and that seemed to get rid of the miss at idle while in gear but on the test run the check engine light started flashing like crazy, which it has never done, it was always steady burn on. Got back to shop checked codes and 300 was in there multiple times as well as the 171 &174 codes. Found I did not get one of the plug wires seated good enough on the #2 coil and it popped off which I am guessing caused the 300 and flashing light. Going to go check that here in a few. I also found this vacuum hose that comes off the passenger side of the intake. It is hooked up at the intake but is cut at a 45* angle a couple feet away and just hanging. Any idea where it "should" go? hoping maybe that might be my lean issue?

.

Re: 2006 chevy express 6.0 codes
 

most likely that's your lean issue. It looks like a hose for like a purge valve. Any emissions valves under the hood missing a hose? Worst case pull it off the manifold and plug it and see if your codes go away. Flashing light was definitely the wire popping off.

Re: 2006 chevy express 6.0 codes
 

With it being in a van it is a pain in the rear trying to see anything on the front of the motor but I will look further for where it needs to hook up to. I am going to plug it until then. I went out and did a small job with it a little while ago and the light did not come on until I pulled back in ( of course I forgot to plug the hose before i left) Good thing was there were no 300 codes this time and it ran really good. Gonna let it cool down some and check some more for the other end of that hose connection and will plug it off if i can't locate it then go for another ride.

Re: 2006 chevy express 6.0 codes
 

Searched for where this hose goes but came up empty handed so far. I plugged it off with a bolt and drove almost 500 miles today and never got a light or any codes so I am happy about that.

Re: 2006 chevy express 6.0 codes
 

That hose most likely feeds the vacuum operated ac vents flaps...

Do your AC / heat system vents cycle when you change from Hot to Cool on the heater switches? Engine running, you should be able to hear the flaps cycle when you move directional switch say from Demist to Cabin air feeds...

Check out this youtube video

https://www.youtube.com/watch?v=V63BGIBnvno


:chevy::chevy::chevy:

Re: 2006 chevy express 6.0 codes
 

That would seem to make sense. I could not get the a/c to come thru the dash vents when I tried it originally. I will check out the video. I would have to get someone else out to listen for the flaps cycling. I lost my hearing several years back.

Thanks to all for the help so far

Re: 2006 chevy express 6.0 codes
 

I just watched the video and then went out to the van. BINGO. looks like I need to order a check valve and some hose. The check valve appears to be totally missing. Slowly but surely I am starting to like this van again :lol:

Re: 2006 chevy express 6.0 codes
 

Good deal! It' didn't dawn on me to say HVAC blend doors, I know the ford E vans still used vac to operate up into the 2000's but thought the GM versions were all electric then.

Re: 2006 chevy express 6.0 codes
 

Upon further searching this morning ( I still had not located the vacuum hose that comes off the check valve going to the controls) I finally located that this morning with the valve still attached. It is all nasty and I am doubtful it is still in working order so i still ordered a new one and some new hose to replace it all. should all be here thursday if not lost in shipping like the last few things

Re: 2006 chevy express 6.0 codes
 

for future note, the flashing Check Engine Light means the engine is misfiring badly...which it would do when a plug wire is off.

if it's a dead hole miss like that, the CEL will flash. If it's intermittent or random misfires...the computer will store the P0300 code and after enough of them the CEL will get set steady on.

Re: 2006 chevy express 6.0 codes
 

Pull a couple of your fuel injectors to see if they are gummed up. Could need a cleaning or replacement. Clogged injectors will cause a lean code.

This could be in addition to your vacuum leaks.

Re: 2006 chevy express 6.0 codes
 

Knock on wood, I have had no more codes since plugging off the vacuum line pictured above. My repair parts should be here today to get it all back together.

Re: 2006 chevy express 6.0 codes
 

Forgot to update this until now but The new hose and check valve fixed both issues. No more codes and all my dash vent functions work properly again.