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I have an 07 Tahoe LT and when driving it will throw up a P0121 code. Then of course the remote start won't work due to the SES light. I called the local dealership and they told me that the throttle body just needs cleaning. Does this sound right? I just went over my warranty a couple months ago. It's been doing this for about a month now. Any thoughts? I know of two other people around here with Silverados too. Just nobody is still in warranty.
99 Camaro LQ9, EPS Cam, Circle D 4400, built 4L65, Moser 9"
2009 Blacked Out Tahoe LT 3" Lift with leveling kit, 20" Rockstars, 35" Terra Grapplers
6.2L, Volant Intake, Polished TB, American Racing LT's/X-pipe
Both Self Tuned with HPT
More or less clean it or replace it! Here are some repair notes from SI summed up a bit:
DTC P0121: Throttle Position (TP) Sensor 1 Performance
The engine control module (ECM) uses the following information to calculate an expected airflow rate:
• The throttle position (TP)
• The barometric pressure (BARO)
• The manifold absolute pressure (MAP)
• The intake air temperature (IAT)
• The engine RPM
• DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0315, P0335, P0336 are not set.
• The engine speed is more than 450 RPM.
• DTC P0121 run continuously when the above conditions are met.
Conditions for Setting the DTC:
The predicted air flow and the predicted MAP combined are outside a calibrated range for more than 3 seconds.
Action Taken When the DTC Sets P0068
• DTC P0068 is a Type A DTC.
• The control module commands the throttle actuator control (TAC) system to operate in the Reduced Engine Power mode.
• A message center or an indicator displays Reduced Engine Power.
• Under certain conditions the control module commands the engine OFF.
Inspect for the following conditions:
• Vacuum hoses for splits, kinks, and proper connections as shown on Vehicle Emission Control Information label
• Inspect thoroughly for any type of leak or restriction
• Air leaks at throttle body mounting area and intake manifold sealing surfaces
• Throttle body for dirt, debris, and coking.
Inspect the throttle body for the following conditions:
• Loose or damaged throttle blade
• Broken throttle shaft
• Any throttle body damage
⇒ If any of these conditions exist, replace the throttle body assembly.
im not sure if it will help, but a had the same problem with my 08 silverado, p0121, it was drivin me nuts, i assumed it had something to do with my ported tb, but i talked to a friend who is a local gm tech, he told me there was a TSB out about it and i needed to clean the throttle body and bring it to him so he could "relearn" the idle..... not sure if its gonna work, im goin up there monday, ill let you know how it works
Pull it off and clean it. Wouldn't bother taking it to a dealer all they are going to do is use some 3m throttle body cleaner and clean it the same way you would. Don't be chicken it's not rocket science. Couple of rags and about an hour worth of time and you're done.