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Juan Crespo
Juan Crespo, Tech Trainer
Category: Saab
Satisfied Customers: 1526
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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Cel light code P0340, replace coils, plugs and sensor no

Customer Question

cel light code P0340, replace coils, plugs and sensor no other codes...when reset code comes back after 3rd start...
bought 6 months ago, working fine...
coils bought from ebay and plugs NGK ...
have taken several trips of > 200mi with no issues...
97K mi. when purchased 102K now.
Will mechanic with diagnostic computer help?
was going to check compression next.
replaced oil twice since purchase both times very dirty, replaced with recommended 0W40
Submitted: 1 year ago.
Category: Saab
Expert:  Juan Crespo replied 1 year ago.

Hi there,

This code refers to a condition where the camshaft might not be synchronized with the crankshaft, therefore combustion might be occurring simultaneously on multiple cylinders. A two-channel scope, not a scan tool is the best tool to verify and diagnose this issue.

How about some background on how this all started? Any symptoms other than the check engine light on?

Customer: replied 1 year ago.
No other symptoms, originally had code P0312 i think, but cleared once soak plugs and coils replaced.
So your recomendation would be to take to a shop that can diagnose in more detail
Expert:  Juan Crespo replied 1 year ago.

Well, I thought I could guide you through all the diagnostic steps, but if you don't have access to the necessary tools, then I do think it would be best to take the vehicle to a qualified repair shop - HINT: ask them if they have a 2-channel scope and a Tech-II scan tool. If they don't, chances are they're not qualified to work on your vehicle. Run for your life... :)

Expert:  Juan Crespo replied 1 year ago.

I have to log out for the day. I’ll be back online ready to continue our conversation tomorrow from 2 to 8 PM EST. Please contact customer service at if you need immediate assistance.