What does it mean?
This is a generic powertrain diagnostic trouble code (DTC) that applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Toyota, Smart, Ford, Mazda, Hyundai, Mercedes, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.
The OBD-II fault code P0902 and related codes P0900, P0902, and P0903 are associated with the clutch actuator electrical circuit. This circuit is monitored by the Engine Control Module (ECM), Powertrain Control Module (PCM), or Transmission Control Module (TCM) depending on the specific vehicle.
The purpose of the clutch actuator circuit is to engage and disengage the clutch or clutches on a semi-automatic transmission. Depending on the specific vehicle and configuration, several sensors and related components are required to accomplish this task. Some configurations incorporate two hydraulic clutches, one for even gears and the other for odd gears. The number of gears can range from 6 to 9 on newer vehicles. Essentially, this design facilitates smooth and seamless gear shifts similar to a fully automatic transmission.
When the ECM, PCM, or TCM detects a low voltage or resistance condition in the clutch actuator circuit, code P0902 is set, and the check engine light or transmission warning light illuminates.
How severe is this DTC?
The severity of this code is normally moderate, but P0902 can be severe if the vehicle does not move properly, which could damage internal transmission components.
What are some of the symptoms of the code?
Symptoms of a P0902 fault code may include:
The engine may not crank
The engine may stall while driving
The transmission may be placed in limp mode
The transmission may be stuck in one gear
Transmission warning light on
Check engine light on
What are some common causes of the code?
Causes of this P0902 code may include:
Faulty clutch actuator
Faulty sensor or solenoid
Defective or damaged wiring
Loose or faulty control module ground strap
Corroded, damaged, or loose connector
Blown fuse or fusible link (if applicable)
Malfunctioning clutch master cylinder
Faulty ECM, PCM, or TCM
What are the troubleshooting steps for P0902?
The first step in the troubleshooting process for any malfunction is to search for Technical Service Bulletins (TSBs) for the specific vehicle by year, model, and powertrain. In some circumstances, this can save a lot of time in the long run by pointing you in the right direction.
The second step is to locate all components associated with the clutch actuator circuit and look for obvious physical damage. Perform a thorough visual inspection to check that the associated wiring does not have obvious defects such as scraping, rubbing, bare wires, or burn marks. Then, check connectors and connections for security, corrosion, and damaged pins. This process should include all wiring connectors and connections to all sensors, solenoids, actuators, and control modules. Consult vehicle-specific technical data to see if a fuse or fusible link is incorporated into the circuit.
Advanced Steps
Advanced steps become very vehicle-specific and require appropriate advanced equipment to perform accurately. These procedures require a digital multimeter and vehicle-specific technical references. The specific technical data will include troubleshooting charts and the proper sequence to follow to help you make an accurate diagnosis.
Voltage Checks
Voltage checks should be performed using the specific troubleshooting guidelines for the vehicle to identify the proper sequence and acceptable ranges for correct operation. This phase of the troubleshooting process will vary significantly by make and model.
If this process identifies the absence of a power source or ground, continuity tests may be required to verify the integrity of the wiring, connectors, and other components. Continuity tests should always be performed with the power disconnected from the circuit, and normal readings for wiring and connections should be 0 ohms of resistance. Resistance or lack of continuity is an indication of faulty wiring that is open or shorted and must be repaired or replaced. A continuity test between the ECM, PCM, or TCM control and the chassis will confirm the service level of the ground straps and wires. The presence of resistance indicates a loose connection or possible corrosion.
What are the common repairs for this code?
Replacement of the clutch actuator
Replacement of a faulty sensor or solenoid
Replacement of the clutch master cylinder
Cleaning corrosion from connectors
Repairing or replacing faulty wiring
Replacement of a blown fuse or fusible link (if applicable)
Repairing or replacing faulty ground straps
Flashing or replacing the ECM, PCM, or TCM
Common Mistake
Replacing a sensor, solenoid, actuator, clutch master cylinder, or control module when damaged wiring is the cause of the problem.
Hopefully, the information in this article has been helpful in pointing you in the right direction to correct the issue with the clutch actuator circuit error code. This article is strictly informational, and the technical data and service bulletins specific to your vehicle should always take priority.