P0902Generic code

P0902 Code: Clutch Actuator Circuit Low

The P0902 code means the clutch actuator control circuit is reading low voltage, either a short to ground or a loss of power. The vehicle may not start or may not go into gear. Check the fuse, relay, connector and wiring 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 P0902 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 P0902 code is set when the circuit shows low voltage, usually a short to ground or a loss of power. 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, unplug the component with the key on and watch the reading or the code. If the value jumps to the opposite extreme, the wiring is good and the component is the one pulling the signal to ground. If nothing changes, look for the short in the wire, starting where the harness rubs against the engine, the chassis or the exhaust.

P0902 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 P0902 code

  1. Control wire shorted to ground. The component can stay on all the time, or the computer cuts the output to protect itself.
  2. Interrupted power supply. A blown fuse, a faulty relay or a broken wire.
  3. Shorted component. Its resistance is far lower than the specification.
  4. Connector with moisture. Water creates a path to ground.

How to diagnose the P0902 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 P0902 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.
  • 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.

P0902 on Opel

Very common on the Opel Easytronic.

P0902 on Fiat

Very common on the Fiat Dualogic.

P0902 on Toyota

Very common on the Toyota MMT.

P0902 on Smart

Seen on Smart vehicles with an automated manual transmission.

P0902 on BMW

Very common on the BMW SMG.

Frequently asked questions about P0902

Can I drive with a P0902 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 P0902?
As a rough guide, between $100 and $1,200. A fuse or a wire repair is cheap, while an actuator replacement with the relearn procedures costs more.
What does the P0902 code mean?
The P0902 code is a generic OBD2 code that means the clutch actuator control circuit is reading low voltage, which points to a short to ground or a loss of power.
Will a P0902 code clear itself?
Only if the cause was a one-time glitch. A real short or a power loss will bring the code back.
What is the most common cause of P0902?
A control wire shorted to ground. After that come an interrupted supply, a shorted actuator and a wet connector.

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