So I've had the P1170 code on my 2004 for a few months now. I can clear it and will stay gone for a few days before it reappears.

I've replaced all 4 O2's with Bosch and had them tested with a live scanner and all are working flawless. Next I checked all my exhaust for any leaks and found nothing. Then I read it could be a vacuum leak so that was next.

Today I smoke tested it using the cigar method and found 2 leaks. One from the intake manifold where the brake servo vacuum line goes into the red plastic piece. The other leak was coming from the throttle body bolt that holds the brackets and spring that the throttle cable hooks to.

Anyway one of these leaks could be causing my code? If not is there anything else worth trying?

 

Have to bump this. It's driving me nuts.

Does no one have any idea of what may be causing this?

 

I feel your pain. I'm sorry no one has any solutions. I get the 1170 every couple months. No idea why. All 4 02s changed and vacuum leaks checked. Still comes up. I just clear it and wait for it to come back a couple months later...

 

Can you get 1170 from plugged cats? It seems I remember reading that. You could try running a fuel injector cleaner to heat up the cats and unplug them a little bit. That might help.

 

So after tightening all the hoses and putting some liquid electrical tape on that odd red hose adapter on the intake manifold I think I've fixed it.

After doing this the code went from P1170 to P0420. I then took it to oreillys and had the code cleared. Hasn't come back after 5 drives so far. I've got my fingers crossed.

Any relation between the two codes?

 

There may be a relationship between the two codes. Here's some info about the P0420 code: JE Robison Service — the blog: Those dreaded P0420/P0430 catalyst efficiency codes and what to do I'm not sure if the system develops a learned fuel map but if it does then once the vacuum leaks were repaired it would suddenly be running too rich. Hopefully the code never comes back.

 

Thanks for the link. I think it probably did learn and the fix caused it to throw the code like you said. Since having the codes cleared it continues to drive and idle better and better.

Only took 6+ months to resolve!

 

My p1170 came back recently and won't go away. It seems it's idling a little rough too. I'll have to look at it when I get some time. Hope it can fix it as you fixed yours.

 

and that is why it is best not to ignore the trouble codes. Better to get them delt with. Im doing the smoke test tomorrow and see what I can do, if no luck then Ill have local LR mechanic figure it out and fix whatever the problem is. Good luck with yours.

PS: Anybody know if a leak in the muffler could trigger a fault code or make it harder for truck to ride up hills?

 

Guess I spoke too soon. Uggghhhhh