Reduced Power Displayed 2003 Chevrolet Tahoe

This 2003 Chevrolet Tahoe with a 5.3 liter engine came in with the customer complaint of the reduced power display was on and the vehicle could not be driven more than about 30 mph. Checking codes found a code p1516 stored for Predicted VS. Actual Throttle Position Correlation Error. That is fancy computer talk for the computer expects the TPS to be in one position and it sees the TPS in another position. There are several things that can cause this condition but by far the most common is a faulty throttle body assembly. I have noticed a disturbing trend in these vehicles in that the last few that I have had to change I also found very weak batteries and the weaker the battery is during cranking the more pronounced the symptom. If the key was left on in these vehicles for more than about five to ten minutes (the time it takes to hook up a scanner and check computer codes and relative data), the starter would turn the engine over very slowly (indicating a weak battery) and sometimes the battery would have to be jumped to start the engine. I may be wrong but it is my belief that a weak battery condition during cranking may be leading to premature failure of the throttle body assembly. My personal philosophy on late model highly computerized vehicles is to replace the battery every three to five years regardless and of course use a good battery and not the cheapest you can find.

Anyways on to changing the throttle body assembly. First remove the upper engine trim cover by first removing the screw and lift off.

Next remove the intake tube that connects to the mass air flow sensor.

Now the intake hose from the throttle body assembly.

Disconnect the clip that holds the intake hose assembly to the radiator hose.

Remove the harness connector from the throttle body by first pulling the gray locking clip back. Depress the lever and remove the connector. Inspect the yellow wire for possible damage as it too can cause the problem, although it seems to be more of a problem in the full sized vans.

There are three nuts that have to be removed.

Next the coolant lines have to come off but first I clamped them both off with hose clamp pliers. Then I took the coolant hose spring clamp and moved it back down the hose so that I could remove the hose from the throttle body. One could use pliers with a little luck and a lot of frustration it will move.

After the hose, next to the alternator is removed the throttle body can be repositioned to make the rest of the job easier.

Off with the old and on with the new. First the passenger side hose is installed. Then the throttle body assembly is put back in place and the driver’s side hose is reattached. In the following picture you can see that I used two pair of hose clamp pliers for the job. It saves having to drain the coolant system and time is money.

Now it is time to put the hose clamp back in place.

The new throttle body is now installed and ready for the intake hose and top trim cover to be replaced.

173 discussions on “Reduced Power Displayed 2003 Chevrolet Tahoe”

  1. Ok like many above I have experienced the REP problem for over two years with many trips to the shop. Code is always the P1125. I have replaced the throttle body, fuel pump (cuz it seems if I get under vehicle and beat on tank it makes it run longer til I get REP), sensor on gas pedal, plugs attached to throttle body and I’m sure I am missing other attempt to fix this issue. Only one that seemed to help was replacing the sensor on gas pedal. After doing so thetryingck ran fine for approx 3 weeks til it started same crap all over again. Now here is further info that I did not see above. I have been driving this truck like this on and off for two years. I attached a cheap code reader and when this happens I just clear code and go until it comes back. Sometimes I can get where I am going with one reset or sometimes it just comes right back on until I stop car, turn engine off, reset code, remove key, open door, shut door, then start vehicle. Even more weird is it will NOT malfunction while using cruise control. I can go 300 miles on cruise with no issues, but as soon as cruise comes off the Dang thing starts malfunctioning. Advise? U think changing computer would resolve? Thx.

  3. Is any of this related to a bad e85 sensor? Mine was bad when I purchased my 03 Tahoe and I have just figured out that a weak battery causes all kinds of havoc with these vehicles everything started with a no start when cold would crank and flood out and thanks to reading this thread for the past half hour I finally know where to look I just started the rep on the display haven’t had it scanned yet but battery replacement and clean of the throttle body is where I will start . Brian

  4. Yo no hablo español y tienen que utilizar el traductor de Google. Por favor, disculpe si los mensajes no son claros. Entiendo que usted tiene una Tahoe 2003 con problemas tps. ¿Tiene un código de diagnóstico del motor?

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