Diagnostic codes, p0174,p0171,p1620

[Eric Hahl]

Hey guys, my wifes 01 330i is running just fine, however; it through up the following OBD 2 codes.

P0171 System too Lean (Bank 1) <--- I understand this. I think.
P0174 System too Lean (Bank 2) <-- and this.
P1620 MAP Cooling Control Circuit Signal High <-- but what is this? Is it related to the others?

Thanks

[Jeron]

Lean in both banks; first thing to check is for cracked or leaking intake tubing.

That engine has a electrically controlled thermostat. Maybe the P1620 is refering to that system.

[Eric Hahl]

Thanks Jeron,

I found a vacuum leak on the air intake. The small vacuum connector on top of the upper air intake hose behind the Mass Air flow sensor was cracked.

I also found a leaky mess of coolant around the thermostat. I happened to have a new thermostat here and was removing the clutch fan and cover to access the thermostat. The clutch fan slipped from my hand and hit the ground breaking a blade off...Doh!

So now instead of this being a 2 hour job its turned into multi day "wait for parts" job, LOL.

[Jeron]

You can get by without the primary fan for a few days easy. Avoid stop and go traffic. Keep and eye on the temp and dont run the A/C.

On the bright side, those brittle fan blades would have broken eventually and probably cut a hose on their way off leaving you stranded.