Fault code P0900 – clutch actuator circuit open

Fault code P0900 is called “Clutch Actuator Circuit Open” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0900

OBD-II fault code P0900 is defined as “clutch actuator circuit open”. Set when the PCM or TCM control module detects that the clutch actuator control circuit is open.

Fault code P0900 – clutch actuator circuit open

The TCM analyzes the actuator output voltage when the clutch is engaged and disengaged, and uses information from various sensors. To calculate the correct torque to change gear.

The gear shift is triggered by a command from the TCM to engage the clutch actuator to disengage the clutch. The various actuators inside the transmission then disengage the current gear. And, depending on the current operating conditions, engage a higher or lower speed.

Some actuators use solenoid-type mechanisms to control the clutch master cylinder. The power in them is transmitted by brake fluid, while other designs use electronic sensors controlled by microprocessors.

Regardless of the design, the goal of all clutch actuation systems is to improve driving by eliminating the need for manual operation.

Computer-controlled clutch actuation systems typically work in dual-clutch systems. Where one clutch controls shifting in even-numbered gears. And the other, controls shifting in odd-numbered gears.

When the control module (TCM) detects an open circuit in the clutch actuator circuit. Code P0900 is set and the engine warning lamp or transmission warning lamp lights up.

Symptoms of vehicle malfunctions

The main signal that an error P0900 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” indicator lamp on the control panel will light up (the code will be stored as a fault).
  2. Transmission warning lamp will light up.
  3. Unable to engage any gear.
  4. The transmission may go into emergency mode.
  5. Transmission may stall in one gear.
  6. The engine may stall while driving.
  7. The engine may not start for safety reasons.

A stored fault code P0900 is considered serious, as it may cause drivability and safety problems with the vehicle. The conditions that contributed to the stored code should be corrected as soon as possible.

Factors that can cause this error code

The error code P0900 can mean that one or more of the following problems have occurred:

  • Faulty clutch actuator.
  • Internal electrical faults in actuator motors or solenoids.
  • Faulty motion or clutch travel sensors.
  • Shorted or damaged wiring harness.
  • Loose or defective control box ground contact.
  • Corroded, damaged or loose connector.
  • Faulty fuse or fusible link.
  • Transmission Control Module (TCM) may be defective.

How to fix or reset OBD-2 code P0900

Some suggested steps for troubleshooting and fix the error code P0900:

  1. Read all stored data and error codes with an OBD-II scanner.
  2. Clear the error codes from the computer memory.
  3. Test-drive the vehicle to see if error P0900 appears again.
  4. Visually inspect the appropriate wires and connectors for damage.
  5. Check the travel or clutch travel sensors.
  6. If necessary, repair the failed components.
  7. Test the transmission control module (TCM).

Diagnose and repair of problems

The first thing to do when diagnosing a P0900 code is to check the electrical part for damage. In today’s vehicles, electrical and electronic signals require good cabling for proper data transmission.

Any faults, such as breaks, disconnected connectors or corrosion, can interrupt signals, leading to transmission control failures. Next, check the battery, as some PCM and TCM modules are sensitive to low voltage.

If the battery is low, the system may detect this as a failure. Make sure the battery is putting out a minimum of 12 volts and that the alternator is running properly, a minimum of 13 volts at idle.

Electrical check

Check the motion or clutch stroke sensors, perform a ground, power and continuity check of all wiring. In addition, be sure to perform an amperage check on the actuator solenoid as well as the actuator position sensor.

These components are part of the control circuit and should be checked along with all others. If necessary, repair or replace the components, then retest the system to see if the code returns.

If all values are within specification, refer to the owner’s manual to find out how to properly energize the clutch actuator mechanism directly. If the mechanism does not respond, check all connections and grounding.

Be sure to check the mechanism for continuity and resistance before applying power directly.

If the mechanism is operating, check it several times for occasional malfunctions or signs of overheating. If the unit overheats or operates erratically, replace it, but remember, some replacements may require reprogramming.

The transmission control module (TCM) fails very rarely, so when diagnosing error P0900, it should be checked if all other checks have already been done.

On which vehicles does this problem occur most frequently

Fault code P0900 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Citroen
  • Ford (E250, Focus, Transit)
  • Hyundai
  • Land Rover
  • Mazda
  • Mercedes-Benz
  • Nissan
  • Peugeot (107)
  • Smart
  • Toyota (Auris, Aygo, Corolla, Yaris)

Fault code P0900 can sometimes be found with other errors. The most common are the following: P0901, P0902, P0903.


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