How to fix codes P0507 and P0174?

VERONICA WIMMS

MEMBER
2009 NISSAN MURANO
3.5L
V6
2WD
AUTOMATIC
159,120 MILES

I've changed the MAF, PCV valve, all emission hoses, cleaned the throttle body and changed the gasket, the spark plugs, and air filter. It's idling rough and at startup the RPMs go almost to two and remain there for a minute. When stopped at a light it doesn't shut off but makes it feel it might any time. Any suggestions on how to fix these codes? Also, my check engine light doesn't light up, but I get codes when I use a scanner, is this normal?

1 Reply

STEVE W.

MECHANIC
13,414 POSTS

The codes both point to a lean condition and unmetered air causing the initial high idle and then the lean condition on bank 2. I would start by doing a few vacuum leak tests around the intake manifold. With a cold engine, start it and then spray carburetor cleaner at the areas where the intake manifold meats the heads, listen for changes in the engine, those will be where the leak is. I suspect it's a manifold gasket leak.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

How to fix codes P0507 and P0174?

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