My XL Denali has a given p0121 code due to intermittent loss of power - not complete loss of power. It’s sluggish when the car idles - like at a stop sign. This happens about once or twice a week. Do you have any suggestions on how to fix this problem?
I recommend inspecting, then cleaning the throttle body if any deposits are found. It's important to do this with key off and disconnect the electrical connector to throttle body. Do not put your fingers in there until it is connected. Push throttle plate and if it sticks or binds replace it. Perform the throttle relearn procedure after cleaning. A scan tool is used to clear any diagnostic codes set during this procedure. If you would like this taken care of, an experienced technician with the right tooling, such as one from YourMechanic, can diagnose the loss of power issue and let you know exactly what actions are needed.
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