LX9 Intermittent DTC/MIL P0300 or Engine Stumble/Hesitation at 5400 RPM or Higher Prior to Transmission Upshift (Replace All Valve Springs with Updated Part Number)

This bulletin is being revised to add the Buick Rendezvous model. Please discard Corporate Bulletin Number 05-06-01-036A (Section 06 -- Engine/Propulsion System).

Some customers may comment on an intermittent " Service Engine Soon" (U.S.) or "Check Engine Soon" (Canada) malfunction indicator lamp (MIL). A DTC P0300 may be stored and/or engine stumble/hesitation at 5400 RPM or higher experienced prior to transmission upshift.

This condition may be due to the engine intake and/or exhaust valve springs floating at 5400 or higher RPM.

Important: The new valve springs, P/N 12599294, will only address the above described bulletin concerns. DO NOT install the new valve springs unless the customer comments match the bulletin concern completely. If the customer comments are not a complete match, then continue on with your diagnosis.

A new engine stiffer valve spring has been released to correct the above condition only. Dealers should install all twelve valve springs with P/N 12599294. Refer to and copy all of the appropriate section(s) of the published service information (SI) before attempting this repair.

For vehicles repaired under warranty, use: