OBD-II trouble code
P2103: Throttle Actuator 'A' Control Motor Circuit High
Voltage on the electronic throttle motor's control circuit is higher than the ECM expects — usually a short to a power source. Throttle control is disabled and the vehicle drops into reduced power mode.
Quick facts
- System
- Powertrain
- Category
- Fuel & Air Metering
- Severity
- High severity
- Drivable
- No — stop driving until repaired
- Repair cost range
- $0 – $900
- DIY difficulty
- Intermediate DIY
What does P2103 mean?
The engine control module (ECM) drives the electronic throttle body's motor through a pair of circuits, reversing polarity between them to open and close the plate. While it drives them, it monitors them. P2103 sets when the ECM measures voltage on the throttle actuator control circuit that is above the expected range for the state it has commanded — the line is sitting high when it should be low, or high beyond what the driver can account for.
On a driven circuit, unexpectedly high voltage almost always means an external power source has found its way in. The typical mechanisms are a chafed wire in the harness touching a battery or ignition-fed conductor, a connector flooded with water or coolant bridging the throttle motor pin to an adjacent powered pin, or aftermarket wiring — alarms, remote starters, auxiliary lighting — spliced into the wrong circuit. A failed driver inside the ECM stuck in its high state is possible but comparatively rare, and should never be the first thing replaced.
P2103 is the mirror of P2102 (circuit low), and the difference matters for how you test. For a suspected short to power, unplug both the ECM connector and the throttle body connector, turn the key on, and probe the motor circuit for voltage. A wire that should be electrically dead but reads battery or ignition voltage is a short to power, and you've found the fault in minutes. For a suspected short to ground you'd instead be measuring resistance to ground. Running the right test for the code you actually have saves a great deal of harness tracing.
The ECM's reaction is the same as with the other actuator circuit faults, and it is deliberately conservative: it de-energizes the throttle motor and lets the plate spring back to its default limp position. The engine idles and the vehicle creeps, but it will not accelerate meaningfully. Treat that as a stop-driving condition rather than an inconvenience. After any repair, run the manufacturer's throttle relearn so the ECM re-establishes the plate's closed position, and confirm in live data that commanded and actual throttle position track together through the full range before returning the vehicle to service.
Common causes
- Chafed throttle motor wire shorted to a battery or ignition power source
- Water or coolant in the throttle body connector bridging the motor pin to a powered pin
- Aftermarket alarm, remote start, or accessory wiring spliced into the throttle circuit
- Corroded terminals creating an unintended path to a powered conductor
- Damaged harness from rodent chewing or a previous repair splice
- Internal fault in the throttle body motor assembly
- Backed-out or misaligned pin in the ECM connector contacting an adjacent circuit
- Failed ECM throttle driver stuck high (rare — rule out the harness first)
Symptoms
- Check engine light with a throttle or reduced-power warning
- Severe loss of power — engine idles but will not accelerate
- Vehicle locked in limp mode with limited RPM
- High or unstable idle at the throttle plate's default position
- Stalling when coming to a stop
- Cruise control disabled
- Other throttle codes such as P2100, P2101, or P2110 present at the same time
Diagnostic steps
- 1.Record all codes and freeze frame before clearing, noting whether the fault is present continuously or only after driving in the wet.
- 2.Inspect the throttle body connector for water, coolant residue, corrosion, and pins pushed back into the housing.
- 3.Unplug both the throttle body connector and the ECM connector, turn the key on, and probe the motor circuit for voltage. Any voltage on a disconnected circuit confirms a short to power.
- 4.If voltage is present, work backward along the harness to find where the circuit is touching a powered conductor.
- 5.Check for aftermarket wiring taps near the ECM and behind the dash — alarms and remote starters are a recurring cause of this fault pattern.
- 6.With everything unplugged, measure the throttle motor's resistance across its pins and compare to specification to rule out an internal fault.
- 7.Inspect the harness for chafe points where it crosses brackets, the cylinder head, or the engine cover.
- 8.After repair, perform the throttle relearn procedure and verify commanded versus actual throttle position in live data through the full pedal range.
Repair cost
$0 – $900
A connector left unlatched or an obvious aftermarket wiring tap can be corrected at no parts cost once identified. Harness repair for a short to power generally runs $150-$450. Electronic throttle body replacement is $300-$800 installed including the relearn. ECM replacement and programming, which should be a last resort here, runs $700-$1,500 on most vehicles.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with throttle body replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.