- Remove the air cleaner outlet duct.
 
- Remove the air inlet screen, if applicable.
 
- Inspect the throttle body bore and the throttle valve plate for deposits. You must open the throttle valve in order to inspect all of the surfaces.
 
Caution: Do not subject a throttle body assembly which contains the following components to an immersion cleaner or a strong solvent:
|    •  | Throttle position (TP) sensor | 
 
|    •  | Idle air control (IAC) valve | 
 
|    •  | Sealed throttle shaft bearings | 
 
The cleaners will damage the electric components or sensors.
The cleaners will damage some of these components that contain seals or O-rings.
Solvents can wash away or break down the grease used on non-serviceable throttle shaft bearings.
Never use a wire brush or scraper to clean the throttle body. A wire brush or sharp tools may damage the throttle body components.
Do not use a cleaner that contains methyl ethyl ketone. This extremely strong solvent may damage components and is not necessary for this type of cleaning.
- Clean the throttle body bore and the throttle valve plate using a clean shop towel with GM Top Engine Cleaner, P/N 1052626 (Canadian P/N 993026) or an equivalent product.
 
- If the deposits are excessive, remove and disassemble the throttle body for cleaning. Refer to 
Throttle Body Assembly Replacement.
 
After disassembly, clean the throttle body using a parts cleaning brush. DO NOT immerse the throttle body in
any cleaning solvent.
- If you removed and disassembled the throttle body for cleaning, assemble and install the throttle body. Refer to 
Throttle Body Assembly Replacement.
 
- Install the air inlet screen, if applicable.
 
- Install the air cleaner outlet duct.