P0123 Dodge

P0123 Dodge — Diagnose and Fix

A P0123 Dodge is defined as Throttle Position Sensor 1 (TPS)  Circuit High. In this case, the PCM is seeing voltage of 4.5 volts or more for at least 1.3 seconds. The TPS used by Dodge is a typical variable resistor with a 5-volt reference voltage input and a ground wire terminating at the PCM. The wiper transmits a return signal with varying voltage that corresponds to the actual throttle position.

Possible causes of P0123 Dodge

A high voltage can be caused by:

TPS sensor circuit shorted to battery voltage
TPS sensor signal circuit is open
TPS sensor signal circuit is shorted to the 5-volt reference supply voltage
TPS ground is open

Test for Reference voltage at TPS

Refer to a shop manual for the exact wire colors for your particular vehicle. In this case, I’ll use a Dodge Durango from the mid 2000’s.

Using a digital multimeter, back probe the pink/yellow wire coming into the TPS. With the key in the RUN position, you should see roughly 5-volts on the pink/yellow wire. Next, check for good ground on the dark blue/dark green wire.

If you see more than 5-volts on the pink/yellow wire, you’ve got a short to battery voltage in one of the splices/junction blocks before the TPS. If you don’t get good ground at the dark blue/dark green wire, you’ve got an open between the sensor and the PCM.

The wiring diagram for a mid 2000’s Dodge Durango shows splice S102 for the 5-volt reference signal and splice S104 for the ground. To check the location of the splices you really need a professional shop manual. Here’s an example.

S102 for the 3.7L engine is located near the breakout for right front oxygen sensor.
S102 for the 4.7L engine is located near top of transmission bell housing
S102 for the 5.7L engine is located on the top front of right cylinder head.
S104 Near breakout for speed input sensor under hood on driver’s side

What shops are seeing as the cause for P0123 Dodge

1) Not using genuine OEM TPS sensor

2) Aftermarket TPS sensor not waterproof. Allows water in during rain/snow that comes in off cowl area

3) Water intrusion into splice S104

©, 2017 Rick Muscoplat