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Automotive Column 30 Reduced Power

Automotive Column 30 Reduced Power

Syndicated Newspaper Column

Many vehicles now have electronic throttle controls (drive by wire) systems. The cables are fading away fast. With this new system the computers are able to limit the throttle functions as it needs to and when this happens due to what is perceived as a failure in the system many vehicles will illuminate a reduced power light and reduce engine power.



Daily Car Repair and Advice Tips Question 30 Reduced Power Light

Dear Motor Medics,
I have a 2003 GMC Pickup with 125,000 miles. Recently while driving it a light on the dash reads Reduced Engine Power with the check engine lamp on and the vehicle speed is limited to approximately 25 MPH. I had a diagnostic scan which returned a code of P1516 and they said everything they could find pointed to the throttle body actuator. Is it possible that the problem could be the throttle body being dirty and running cleaner through the gas tank will help? If the throttle body needs to be replaced, what should I expect the cost to be? P.S. this has happened about three times in the last 150 miles.

Dwight in Worthing South Dakota

Dear Dwight,
GM light duty trucks now have this type of electric throttle system to control engine speed and cruise control. The system is a very sound one with several sensors to act as backups for the other so the system can tell if there is a failure and can shut it down or limit power for safety. The code you have tells me that the engine has seen a circuit failure in the throttle body. This means the throttle body sensors or the wiring to them may have failed. Cleaning will not help this one or have prevented the failure. You will need to have a shop use a lab scope to read the voltages to verify the problem. Check around for local pricing.

Take care, the Motor Medics
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Advice given by the Motor Medics is for entertainment only. Each problem is different and requires different approaches and answers given here are opinions and just one possibility. Always follow all recommended safety procedures and consult with your own qualified technician before attempting repairs of any kind.

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