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32valvesftw · 07-13-2016

For future reference, the GM Service Technology Group Fuel and Emissions Course handbook, states that Code 55 is "Fuel Lean Monitor" It gives 3 possible causes
1. Secondary ignition insulation fault
2. Lean Injector
3. Inlet filter restriction to injector.

Code 64 is "right Oxygen Sensor signal-lean"
It gives several causes one of which is injector restriction - right bank

So it looks to me like you nailed it by changing out the offending injector. Good work.

07-13-2016	#8
32valvesftw Join Date: Jun 2015 Location: Texas Posts: 529	Re: Code help h55 and h64 For future reference, the GM Service Technology Group Fuel and Emissions Course handbook, states that Code 55 is "Fuel Lean Monitor" It gives 3 possible causes 1. Secondary ignition insulation fault 2. Lean Injector 3. Inlet filter restriction to injector. Code 64 is "right Oxygen Sensor signal-lean" It gives several causes one of which is injector restriction - right bank So it looks to me like you nailed it by changing out the offending injector. Good work.