Hi Everybody,

I figured I would post about a recent experience I had with po175 popping up accompanied by restricted performance to possibly help others in the future.

This all happened after removing my car from winter storage, connecting battery, and attempting to complete the OBD2 cycles. Every OBD cycle would complete itself except for the catalyst cycle, then the po175 would pop up with restricted performance. Po132 and po152 would also pop up in "pending codes" but don't focus on that.

Naturally I monitored my trims and they were off, indicating a vacuum leak. So normal protocol right? Checked part load, full load breather, intake junctions, throttle body elbow connects, and cleaned the maf. Code came back. I started to worry that since my air filter is directly force fed by a hood vent that maybe the ECU was forcing richness do to too much fresh air feed at speed. I deducted because I find overthinking generally does not work out and from past experiences this would not be true, so I ruled that out before I even gave it a chance.

So my search for a leak moved on. After going through every hose, I put on my glasses Looking closer at the evap system now, at the purge valve I noticed what looked like a hairline fracture in the t fitting that connects to the vacuum hose.

In diagram E32571 the T-fitting has (1) pointing at it


Sure enough on disassembly the brittle 18 year old plastic practically crumbled in my hands. I replaced the t-fitting and viola, no more po175 and OBD cycles complete!! Hope this tip can help others if po175 happens to make an appearance and you have trouble tracking it down. Have a good day folks

 

Nice info greverrr, I have an intermittent issue (P0455) that is somewhat similar (I already replaced the filler cap). I'm going to be replacing the purge valve and the canister line between the two if the valve doesn't solve it. Its so intermittent that I'm pretty sure its the valve.
Thought it would be nice to mention it here, since we're in the emissions area.

 

I think you are right in replacing the purge valve first and canister hose to follow. EVAP codes IMO are hard to make final diagnoses' on being that they are almost always consistently inconsistent and may times vague. Case in point, my car passed the EVAP drive cycle with faulty vacuum just fine, but throws me the bank 2 rich code.