2018 Encore P-0171-00

[erndog]

I was having P-0171-00 and O2 codes for the downstream sensor. I replaced the sensor and the CEL cleared and stayed out for about 15 miles. During a hard acceleration the CEL came on again with a P-0171 code.
I did the paper test at idle on the oil fill cap. No suction, but a ton of positive pressure. I also checked the little hole on the PCV. Essentially no suction there.
Does this mean the check valve on the intake manifold is shot? I stuck a scope down the hole, but it is so oily I couldn't determine if it is intact or not. Is the purge canister a possibility? I saw something referring to that in a thread.
Any advice is appreciated.

 

[DocBrown]

I was having P-0171-00 and O2 codes for the downstream sensor. I replaced the sensor and the CEL cleared and stayed out for about 15 miles. During a hard acceleration the CEL came on again with a P-0171 code.
I did the paper test at idle on the oil fill cap. No suction, but a ton of positive pressure. I also checked the little hole on the PCV. Essentially no suction there.
Does this mean the check valve on the intake manifold is shot? I stuck a scope down the hole, but it is so oily I couldn't determine if it is intact or not. Is the purge canister a possibility? I saw something referring to that in a thread.
Any advice is appreciated.

Which engine, LUV or LE2? LUV is engine code "B" on 8th digit of your VIN #, LE2 is engine code "M".

 

[erndog]

B, so LUV

 

[DocBrown]

B, so LUV

More than likely this is caused by a clogged PCV valve. It's not that hard to change the valve cover, so if you have the tools and take your time, it would be worth
doing.

 

[erndog]

More than likely this is caused by a clogged PCV valve. It's not that hard to change the valve cover, so if you have the tools and take your time, it would be worth
doing.

Ok.
Is that more likely than a bad intake check valve?

 

[DocBrown]

Ok.
Is that more likely than a bad intake check valve?

What you are calling an intake check valve is the PCV valve. Common issue.

 

[erndog]

Solved...so far.
I replaced both the intake manifold and the valve cover. All codes are gone for the time being.