What does it mean?

This is a generic powertrain diagnostic trouble code (DTC) that applies to many OBD-II vehicles (1996 and 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 P0900 and related codes P0901, P0902, and P0903 are associated with the clutch actuator 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 incorrect voltage or resistance in the clutch actuator circuit, code P0900 will be set, and the Check Engine light or Transmission Warning light will illuminate.

How severe is this DTC?

The severity of this code is normally moderate, but P0900 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 P0900 fault code may include:

• The engine may not crank
• The engine may stall while driving
• The transmission may enter limp mode
• The transmission may be stuck in one gear
• Transmission warning light illuminated
• Check Engine light illuminated

What are some common causes of the code?

Causes of this P0900 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 P0900?

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 chafing, 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 must be performed using the specific troubleshooting guidelines for the vehicle to identify the correct sequence and acceptable ranges for proper operation. This phase of the troubleshooting process will vary significantly between makes and models.

If this process identifies a missing 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 indicates 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 serviceability 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?

• Replacing the clutch actuator
• Replacing a faulty sensor or solenoid
• Replacing the clutch master cylinder
• Cleaning corrosion from connectors
• Repairing or replacing faulty wiring
• Replacing a blown fuse or fusible link (if applicable)
• Repairing or replacing faulty ground straps
• Reprogramming 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 fault code. This article is strictly informational, and the specific technical data and service bulletins for your vehicle should always take priority.

What does it mean?

This is a generic powertrain diagnostic trouble code (DTC) that applies to many OBD-II vehicles (1996 and 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 P0901 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 an out-of-range performance issue or other problem with the voltage or resistance in the clutch actuator circuit, code P0901 will be set, and the check engine light or transmission warning light will illuminate.

How severe is this DTC?

The severity of this code is normally moderate, but P0901 can be severe if the vehicle is not moving properly, which could damage internal transmission components.

What are some of the symptoms of the code?

Symptoms of a P0901 fault code may include:

• The engine may not crank
• The engine may stall while driving
• The transmission may go into limp mode
• The transmission may be stuck in one gear
• Transmission warning light illuminated
• Check engine light illuminated

What are some common causes of the code?

Causes of this P0901 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 P0901?

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 chafing, 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 a missing 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 indicates 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 serviceability of ground straps and wires. The presence of resistance indicates a loose connection or possible corrosion.

What are the common repairs for this code?

• Replacing the clutch actuator
• Replacing a faulty sensor or solenoid
• Replacing the clutch master cylinder
• Cleaning corrosion from connectors
• Repairing or replacing faulty wiring
• Replacing 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 fix the issue with the clutch actuator circuit error code. This article is strictly informational, and the specific technical data and service bulletins for your vehicle should always take priority.

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.

What does it mean?

This is a generic powertrain diagnostic trouble code (DTC) that applies to many OBD-II vehicles (1996 and 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 P0903 and related codes P0900, P0901, 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 in 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 in 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 high voltage or resistance condition in the clutch actuator circuit, code P0903 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 P0903 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 P0903 fault code may include:

The engine may not crank
The engine may stall while driving
The transmission may go into 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 P0903 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 P0903?

The first step in the troubleshooting process for any malfunction is to check for Technical Service Bulletins (TSBs) for the specific vehicle by year, model, and powertrain. In some cases, 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 ensure the related wiring has no obvious defects such as chafing, rubbing, exposed 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 correct sequence and acceptable ranges for proper operation. This phase of the troubleshooting process will vary significantly by make and model.

If this process identifies a missing 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 indicates 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 serviceability of ground straps and wires. The presence of resistance indicates a loose connection or possible corrosion.

What are the common repairs for this code?

Replacing the clutch actuator
Replacing a faulty sensor or solenoid
Replacing the clutch master cylinder
Cleaning corrosion from connectors
Repairing or replacing faulty wiring
Replacing 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 guiding you in the right direction to fix the issue with the clutch actuator circuit error code. This article is strictly informational, and the specific technical data and service bulletins for your vehicle should always take priority.

What does the P0904 code mean?

Today’s transmissions, whether manual, automated manual, adaptive dual-clutch, or automatic, are more monitored and, in some cases, controlled by the engine control module and the transmission control module (ECM and TCM). In some vehicles, the TCM may be integrated into the ECM. In automatic and automated manual transmissions, the ECM and TCM work together to modulate engine output and transmission engagement, even adjusting gear engagement to be as smooth or powerful as desired. Even in manual and adaptive dual-clutch transmissions, the ECM monitors TCM and transmission readings to perform precisely timed throttle cuts and refine engine output.

Depending on the type of transmission and the car manufacturer, the TCM may use various sensors to monitor and control the transmission, such as speed sensors, pressure sensors, and temperature sensors. Many of these transmissions also have gate select position (GSP) sensors, which can be mounted on the transmission, the gear lever, or the shift linkage. The position sensors inform the TCM which gear the driver has commanded for at least two reasons.

In some transmissions, such as automated manual transmissions or automatic transmissions with manual mode, the GSP switch lets the TCM know whether the driver has selected automatic or manual function. In manual transmissions, the GSP switch informs the TCM of the gear the driver is selecting and can act as a neutral safety switch, depending on the system design. The TCM also uses the gate select position switch to monitor transmission operation. For example, if the driver selects manual mode and chooses 3rd gear in an automatic transmission, the TCM can monitor speed sensors to detect clutch and brake slippage.

If the ECM detects a problem with the GSP sensor circuit, it will store a diagnostic trouble code (DTC) in memory and illuminate the MIL (malfunction indicator light). DTC P0904 is defined as “Transmission Gate Select Position Circuit Malfunction” and may be accompanied by other GSP sensor codes, such as P0905, P0906, P0907, or P0908.

What are the common causes of the P0904 code?

Depending on the year, make, and model, DTC P0904 can have several causes. Here are some of the most common ones.

Misalignment – This often occurs after a transmission repair, which may have involved the sensor itself, the shift linkage, or the entire transmission. The technician may have misaligned the sensor or neglected to tighten its mounting bolts properly. If the sensor is misaligned or slips, it may not correctly report the gear select position, causing this issue. Fortunately, alignment is usually a simple adjustment. Use Loctite Blue 242 or similar to prevent bolts from backing out after adjustment.
Faulty sensor – As with all electronic devices, the GSP sensor can fail. Sensors exposed to the elements or spilled coffee in the console can easily lead to corrosion and failure.

What are the symptoms of the P0904 code?

Depending on the system design, you may or may not experience issues beyond the MIL. Some symptoms may include the inability to start your vehicle, irregular shifting, hard or delayed gear engagement, or “missing” gears.

How do you troubleshoot the P0904 code?

Since this DTC refers to a circuit problem, you will need at least a DVOM (digital voltmeter) to diagnose the GSP sensor and the circuit between it and the ECM or TCM. A scan tool with live data streaming capabilities can also be helpful for diagnosis, as it will show you what the ECM or TCM is seeing. Usually, circuit issues, such as loose connections, corrosion, or a damaged wiring harness, cause this DTC to be recorded, but alignment problems can potentially trigger this issue.

Sensor alignment – First, check the sensor alignment. The scan tool can be useful for this step. Adjust as needed.
Rotary sensors usually need to be aligned to a “neutral baseline” to correctly detect the gate select position. If it’s off to one side or the other, GSP voltages may be biased to one side, or the TCM may detect more than one position at a time. Ensure the sensor mounting screws are properly tightened to prevent sensor housing movement.
GSP sensors on the gear lever or shift linkage may rely on physical contact, with tabs or buttons forming the basis of these sensors or switches. Over time, plastic or metal tabs can weaken, bend, or break. At least a few brands use magnetic micro-switches to detect position, and magnets are known to come loose. Repair or replace any obviously damaged parts.

Circuit checks – You will need an EWD (electrical wiring diagram), specific to your year, make, and model, to diagnose the circuit operation between the ECM and the GSP.
Inspect the GSP sensor, connector, wiring harness, and ECM or TCM connector for obvious damage. Check connectors for corrosion or evidence of water entry, and check for aged or loose pins. Ensure all connectors are properly installed. Repair if necessary.
Disconnect the ECM and GSP and check for continuity.
If you measure more than 5 Ω, repair the wiring harness as needed. If you measure less than 5 Ω, suspect a faulty GSP sensor, but do not condemn it until you have completed circuit checks.
Check for short circuits between each line and from each line to ground. If you measure resistance less than 10 kΩ, repair the wiring harness as needed. If you measure more than 10 kΩ, suspect a faulty GSP sensor.
If the diagnostic tool and circuit diagnostics yield no issues, you may have a faulty ECM or TCM, but this is not common.

How serious is the code?

Unless the engine and transmission computers know which gear has been selected, you may experience a number of transmission and engine issues such as difficult gear changes and a no-start condition. Therefore, a P0905 diagnostic code is quite serious.

Symptoms

Symptoms of a P0905 include:

• Engine does not start
• Transmission behaves erratically
• Difficult gear shifts
• Transmission delays before shifting
• Cruise control no longer works properly

Causes

• Gate select position sensor is misaligned
• Shift linkage adjustment issue
• Faulty GSP sensor

How to diagnose the code?

Problems with the gate select position sensor often occur after transmission repairs have been performed. Therefore, the first step in diagnosing an OBDII P0905 fault code is to check the GSP sensor adjustment. It may also be necessary to check the shift linkage alignment.

What repairs will fix P0905?

1. Adjust the gate select position sensor
2. Adjust the shift linkage
3. Replace the GSP sensor