P0903Generic code

P0903 Code: Clutch Actuator Circuit High

The P0903 code means the clutch actuator control circuit is reading high voltage, either an open circuit or a short to voltage. The vehicle may not start or may not go into gear. Check the connector, the wiring, the fuse and the relay before you replace the actuator.

Severity
High
Can I keep driving?
Yes, but with caution
Estimated cost
$100 to $1,200
Difficulty
Medium
System
Transmission
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0903 code means

Automated manual transmissions (Opel Easytronic, Fiat Dualogic, Toyota MMT, BMW SMG, Ford Durashift, Volkswagen ASG) and many dual clutch transmissions use electric or hydraulic actuators to disengage the clutch, to choose the gear plane (select) and to engage the gear (shift). The transmission computer watches every actuator with position sensors. The clutch actuator releases and applies the clutch when you pull away and on every shift.

The computer monitors the control circuit through its own driver transistor. The P0903 code is set when the circuit shows high voltage, usually an open circuit or a short to voltage. Before you replace the component, check the fuse, relay, connector and wiring, because those are the most common causes.

If the actuator does not respond, the vehicle may not start (the clutch does not release), may not go into gear or may jerk when pulling away. After any repair of these components you must run the transmission relearn procedures with a scan tool (clutch touch point, select and shift positions). Without them the transmission will not work properly.

To confirm the fault, measure the continuity of each wire between the component connector and the computer connector with the key off. It should be under 1 ohm, and an infinite reading means the wire is open. If the wiring is good, measure the component itself. An infinite resistance confirms it is open inside.

P0903 code symptoms

  • Check engine light or another warning light on.
  • The vehicle will not start or will not go into gear.
  • The transmission does not engage gears or stays in neutral.
  • Transmission or engine warning light on.
  • Beep or warning message in the instrument cluster.

Likely causes of the P0903 code

  1. Loose or broken connector. The most frequent cause, especially right after another repair.
  2. Open coil or motor. The resistance reads infinite.
  3. Cut control wire between the component and the computer.
  4. Short to 12 volts. The control wire touches another wire that carries voltage.

How to diagnose the P0903 code step by step

  1. Command the component with the scan tool and check whether it responds.
  2. Check the fuse and the relay. Measure voltage on both sides of the fuse, and swap the relay with an identical one.
  3. Measure the supply at the connector. You should see battery voltage with the key on or when the component is commanded.
  4. Measure the resistance of the component and compare it with the manual. Also check its insulation to ground.
  5. Check the control wire. Confirm continuity all the way to the computer and make sure there is no short.
  6. Activate the actuator with the scan tool and see whether it moves.
  7. Run the transmission relearn procedures after any repair.
  8. Check the hydraulic fluid level and look for leaks.

How to fix the P0903 code

  • Repair the connector, the wiring or the power supply.
  • Replace the clutch actuator if it does not respond even with correct power and control signals.
  • Clear the codes and verify the repair.

Technical reference data

  • Electric actuator (DC motor) or a hydraulic solenoid valve controlled by a PWM signal.
  • Wire continuity between connectors: below 1 ohm.
  • Approximate values only: check the manufacturer data for your vehicle.

Brand-specific notes

This code is very common on automated manual transmissions. On many hydraulic systems the actuator fluid is a specific type and the reservoir should be checked regularly.

P0903 on Opel

Very common on the Opel Easytronic.

P0903 on Fiat

Very common on the Fiat Dualogic.

P0903 on Toyota

Very common on the Toyota MMT.

P0903 on Smart

Seen on Smart vehicles with an automated manual transmission.

P0903 on BMW

Very common on the BMW SMG.

Frequently asked questions about P0903

Can I drive with a P0903 code?
Only with caution and only as far as the shop. The transmission can lose its gears at any moment.
What does the clutch actuator do?
Automated manual transmissions (Opel Easytronic, Fiat Dualogic, Toyota MMT, BMW SMG, Ford Durashift, Volkswagen ASG) and many dual clutch units use electric or hydraulic actuators to release the clutch, select the gear plane and engage the gear. The computer watches each one with position sensors. The clutch actuator releases and applies the clutch when you pull away and on every shift.
Do I always have to replace the part?
No. Check the fuses, relays, connectors and wiring first. They are the usual causes and cost much less than a new actuator.
How much does it cost to fix P0903?
As a rough guide, between $100 and $1,200. A connector or wire repair is cheap, while an actuator replacement with the relearn procedures costs more.
What does the P0903 code mean?
The P0903 code is a generic OBD2 code that means the clutch actuator control circuit is reading high voltage, which points to an open circuit or a short to voltage.
Will a P0903 code clear itself?
Only if the cause was a temporary glitch. A loose connector or an open wire will bring it back.
What is the most common cause of P0903?
A loose or broken connector, especially after another repair. An open actuator and a cut control wire follow.

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