'08 23 LSV Crank Sensor error SPN 636 (340 monsoon)

[SmoothCriminal]

2008 23 LSV 340 Monsoon: Last 2 weeks getting 'service required' interruption while running, no performance loss. When slow to neutral engine wants to stall out and then code goes 'engine fault' (which is crank sensor SPN 636 inaccurate or intermittent data) and does not want to re-start. Where is crank sensor and is this likely faulty sensor or something else?

[justgary]

I don't know specifically about your engine, but last time I looked for a GM crank sensor it was low and beside the harmonic balancer. Look for a small sensor with probably three wires on the pulley/belt end of the engine, very near the crank pulley.

They do go bad, but it could also be a wiring issue, especially if you have had it in for service and someone was probing around.

[Maltech]

Your crank sensor is by the harmonic balancer. Or the port side. It's possible that it is faulty. But it most likely needs a shim installed between it and the timing chain cover

[SmoothCriminal]

Thanks for the insight. I've found the sensor and have a new one on order.

[Bozboat]

do all monsoon engines have a crank position sensor or just some of the newer ones?

[justgary]

I think it's just the newer ones that run closed loop. Not really needed for open loop, bank fired injection.

[SmoothCriminal]

Back again - new crank sensor installed - still have the same issue. I spoke to another mechanic that said it might be the IAC (Idle Air Control) valve. Any thoughts on this? That seems to be my next step so i'll try to locate it, pull it off and see if it's stuck or something.

[justgary]

That makes sense, but I would clean the throttle body before throwing more parts at it.

[justgary]

By the way, the crank sensor code may have been because of the stall, not the cause of the stall. A MEFI reader will show you engine data in real time.