P0805 – Clutch position sensor -circuit malfunction

Reinier

By Reinier (Contact Me)
Last Updated 2017-11-07
Automobile Repair Shop Owner

Trouble CodeFault LocationProbable Cause
P0805 Clutch position sensor -circuit malfunction Wiring, poor connection, clutch position sensor, ECM/PCM!TCM

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What Does Code P0805 Mean?

OBD II fault code P0805 is a generic code that is defined as “Clutch Position Sensor Circuit”, and is set when the PCM (Powertrain Control Module) detects an abnormal voltage and/or resistance in the clutch position sensor circuit. Note that this code applies only to applications with manual transmissions.

On applications that are fitted with clutch position sensors, the sensor monitors the position of the clutch pedal to allow the sensor to act as a safety cutout switch. In practice, the sensor interrupts the power supply to the starter motor to prevent the engine from starting unless the clutch is disengaged.

In terms or operation, the clutch position sensor is usually a simple on-off switch that is always supplied with battery power on one side when the ignition is in the “ON” position. When the clutch pedal is depressed, contacts in the switch are closed, which passes current through the switch to the starter. From a safety perspective, the practical advantage of this is that in a fully functional system, the engine cannot be started unless the transmission is decoupled from the engine, much like the engine in an automatic vehicle cannot be started unless the transmission in either the NEUTRAL or PARK position.

Thus, when the PCM detects an abnormal voltage or resistance in the clutch position sensor or its control circuit, it will set code P0805 as a result, and depending on the application, may or may not illuminate a warning light.

Where is the P0805 sensor located?

On most applications, the clutch position sensor is located directly on, or near the clutch pedal to allow the clutch pedal itself to act on the switch when the pedal is depressed. The image below shows the typical location of a clutch position sensor. The large red arrow indicates the switch itself, while the smaller yellow arrow points to the wiring connector. Note though that while the actual appearance and mounting method of clutch position sensors vary greatly between applications, this switch is almost invariably the only switch that is mounted on or near the clutch pedal.

What are the common causes of code P0805 ?

Some common causes of code P0805 could include the following-

  • Defective clutch position sensor/switch
  • Damaged, shorted, burnt, disconnected, or corroded wiring and/or connectors
  • Incorrect adjustment or alignment of the switch

How expensive is it to fix code P0805 ?

On most applications, the replacement cost of a clutch position sensor varies from around $25 on the low end, to about $70 on the high end if the replacement is done on a DIY basis. Note that most repair shops will levy a minimum one-hour labour charge on top of the price of the switch, so shop around for the best labor rates.

Note that this repair estimate does not include relevant fees and taxes that may be payable if the sensor replacement is performed professionally at a repair shop.

What are the symptoms of code P0805 ?

Some common symptoms of code P0805 could include the following-

  • Stored trouble code, and in some cases, an illuminated warning light
  • On some applications, the code may be stored as “pending” until a set number of failure cycles had been registered
  • Depending on the application, and the nature of the problem, the engine may not crank even when the clutch pedal is fully depressed
  • In most cases, the engine will crank and start without the need to depress the clutch pedal
  • In rare cases, there may be no symptoms at all

What are common solutions to code P0805 ?

Common solutions to code P0805 usually include the following-

  • Replacement of the clutch position sensor
  • Correcting switch adjustment/alignment issues
  • Repair or replacement of damaged/defective wiring
  • In rare cases, the PCM may have to be reprogrammed after a clutch position sensor replacement

How serious is code P0805 ?

The seriousness level of this code is moderate, since in some cases, the engine cannot be started until the fault is corrected. Note though that if the engine can be started with this code present, the code does not produce driveability issues, or cause damage to parts and components if it is not immediately resolved.

How safe is it to still drive the car with code P0805 ?

If the engine can be started with this code present, great care must be taken when doing so since it is easy to forget that the manual transmission might be in gear. Starting a manual vehicle while it is in gear could cause the vehicle to lurch forward into other vehicles and /or obstacles, or worse, injure children, pets, and bystanders.

How difficult is it to repair code P0805 ?

Apart from the fact that the clutch position sensor is sometimes difficult to access, the testing and replacement of the switch should not present the average non-professional mechanic with undue difficulties. Be aware that in some cases, it may be necessary to remove trim panels or parts of the dashboard to gain easy access to the sensor.

Note that a good quality digital multimeter and a wring diagram for the affected application are required to diagnose this code accurately.

What are the common mistakes when repairing code P0805 ?

Common mistakes when dealing with this code usually include the following-

  • Failure to check and where possible, to correct switch adjustment issues
  • Condemning the starter motor or starter solenoid without verifying the operation (or otherwise) of the clutch position sensor
  • Failure to verify that full battery voltage is available at the powered terminal of the sensor
  • Failure to verify that full battery voltage passes through the switch when the contacts are closed

 

How do you troubleshoot code P0805 ?

Step 1

Record all fault codes present, as well as all available freeze frame data. This information can be of use should an intermittent fault be diagnosed later on.

NOTE: If other codes are present, and particularly codes that relate to system voltages, these codes must be resolved before an attempt is made to diagnose code P0805.

Step 2

Assuming no additional codes are present, locate and identify the clutch position sensor. Inspect the switch for obvious signs of damage, overheating, or misalignment/maladjustment.

NOTE: If the sensor is adjustable, refer to the manual for details on the correct adjustment procedure to follow, since over adjustment can damage the switch when the clutch pedal is depressed, while under adjustment can prevent the switch from working when the pedal is depressed.

If the switch is free of visible damage, inspect the electrical connector for looseness, damage, corrosion, or other defects, and make repairs as required.

Step 3

If no visible damage is found, determine the function and color-coding of each wire in the connector. Identify the power supply, and verify that full battery voltage is available at the connector.

If no voltage is present, or if the voltage is significantly below battery voltage, inspect this wire for damage, and/or open circuits, and make repairs or replace wiring as required. Retest the voltage in the power supply wire after repairs are complete to verify the full battery voltage is available.

NOTE:  Loss of ground can also cause battery voltage not to be available at the sensor. Thus, be sure to check all ground straps for tightness and continuity. Also, be sure to verify that all fuses in the circuit are serviceable.

Step 4

If full battery voltage is present at the connector, activate the switch manually while monitoring the output terminal with the multimeter. If full battery voltage passes through the switch, correct the switches’ alignment or adjustment if it is adjustable.

NOTE: Be aware that long use can wear out some parts in the switch to the point where it no longer works even if the clutch pedal is depressed fully. Therefore, if the switch passes a current when it is activated manually but the switch fails to pass a current when the clutch pedal is depressed, suspect excessively worn moving parts in the switch itself. Replacement of the switch with an OEM replacement is the only reliable remedy.

NOTE #1: If the clutch position sensor passes full battery voltage, be sure to verify that the current reaches the starter motor solenoid by checking that battery voltage is available at the starter solenoid connector when the ignition is turned to the “START” position. If no voltage is present, or if the voltage is significantly below battery voltage, inspect this wire for damage or open circuits, and make repairs or replace wiring as required to ensure that full battery voltage reaches the starter motor solenoid. Be sure to include the starter motor relay in this inspection.

Step 5

If full battery voltage is available at the clutch position sensor but no, or very little current passes through it when it is activated, the switch is defective and it must be replaced.

If the witch is adjustable, make sure that is adjusted correctly to ensure proper operation. Verify that the replacement switch is adjusted correctly by confirming that full battery voltage passes through it when the clutch pedal is depressed fully. Equally importantly, verify that no current passes through the switch when it is in “OFF” position.

Clear the code after all repairs are complete, and operate the vehicle for at least one complete drive cycle before scanning the system again to see if the code returns.

Step 6

Steps 1 through 5 will resolve this code in nine out of every ten cases, but if the code persists, suspect an intermittent wiring issue, or intermittent failures of the switch itself. If an intermittent fault is suspected, repeat all the steps outlined above until the fault is found and repaired, or refer the vehicle to a competent repair facility for professional assistance.

Codes Related to P0805

  • P0806 – “Clutch Position Sensor Circuit Range/Performance”
  • P0807 – “Clutch Position Sensor Circuit Low”
  • P0808 – “Clutch Position Sensor Circuit High”
  • P0809 – “Clutch Position Sensor Circuit Intermittent”
  • P080A – “Clutch Position Not Learned”

 

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