The OBD2 code P0805 signals an issue with the circuit of the clutch position sensor, which is a crucial component for vehicles with manual or semi-automatic transmissions. This sensor informs the car’s computer (ECU or TCM) about the position of the clutch, facilitating smooth gear shifts and optimal driving performance.
P0805 quick overview
| Meaning | P0805: Clutch Position Sensor Circuit |
| Is it serious? | Yes, it can lead to difficulties in gear selection, potential stalling, and may even prevent the vehicle from starting. |
| Possible causes | – Faulty clutch position sensor – Wiring or connector problems in the sensor circuit – Issues with the transmission control module (TCM) – Mismatched components in the clutch system |
| How to diagnose? | Inspect the clutch position sensor and its connections for any signs of damage or wear. Check the wiring and connectors for shorts, breaks, or corrosion. Test the sensor’s functionality with a diagnostic scanner or multimeter. Ensure all clutch-related components are compatible and functioning correctly. |
P0805 Meaning
The clutch position sensor acts much like a communicator, relaying vital information about the clutch’s position back to the car’s computer system. When this sensor isn’t working properly, it’s akin to having a broken phone; messages get lost or misinterpreted, leading to gear shifting issues, stalling, or difficulty starting the car.
It’s essential for this sensor to be in top condition to ensure your vehicle understands when and how to engage or disengage the clutch, ensuring a smooth and responsive driving experience.
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- Car Electrical basics
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How to fix P0805 – learn from mechanics
I looked into P0805 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Aston Martin
Vehicle Information:
- 2003 Aston Martin Vanquish S 6.0L
Issue + Repair History:
- P0805 hard code for clutch position sensor
- Another shop previously replaced the throwout (T/O) bearing with the clutch position sensor for the same fault code (P0805)
- Concerns about the sensor’s condition, potential TCM issue, and location of TCM for continuity check
1st resolution, but code is back:
- Installed an updated throwout bearing along with a matching clutch position sensor
- Emphasized the importance of using matching components
- Reflashed the transmission ECU
Additional Information:
- The specific transmission type or code was not provided
Final Fix:
- Installing the updated throwout bearing along with a matching clutch position sensor resolved the issue.
Case #2: Mazda
Vehicle information 2010 Mazda 3 i 2.0L
Issue + repair history:
- Complaint of setting P0805 code after half-hour of driving.
- Previous repair: Transmission fluid changed and filter replaced.
Other OBD2 Codes + Test Results
- P0805 (clutch position sensor circuit)
- U0101 stored in every module.
- Unable to communicate with TCM via Snap-On Solus Edge.
Mechanic suggestions
- Check all power and grounds to TCM with a headlamp.
- Inspect associated transmission harness for any damage or rubbing.
- Test continuity of the wiring.
Final fix Discovered TCM losing ground for the Oil pressure sensor. Replaced defective TCM, and issue resolved.
Case #3: Dodge
Vehicle information 2007 Dodge Ram 3500 ST 6.7L
Issue + repair history:
- Intermittent limp mode at highway speeds, especially in high gear.
- Previous repair: Reflashed all control modules with latest software versions.
Other OBD2 Codes + Test Results
- P0805 (clutch position sensor circuit)
Mechanic suggestions
- Some mechanics suggest investigating a possible transmission rebuild.
- Check transmission harness for chafing or damaged wires due to diesel engine vibration.
Final fix After driving and allowing the vehicle to idle for prolonged periods to maximize heat build-up, discovered a bad transmission. Installed a remanufactured unit, and issue resolved.
How to diagnose P0805
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Diagnostic Step | Brief Explanation |
|---|---|
| Inspect sensor and connections | Look for physical damage or wear that could impair the sensor’s ability to function. |
| Check wiring and connectors | Identify and repair any electrical issues that could affect signal transmission. |
| Test sensor functionality | Use diagnostic tools to confirm the sensor is operating within its expected range. |
| Verify component compatibility | Ensure that all parts related to the clutch system work together seamlessly, avoiding mismatched components. |
These cases illustrate the critical nature of correctly diagnosing and resolving issues indicated by the P0805 code. Whether it’s ensuring the use of matching components in the clutch system, addressing electrical faults in the sensor circuit, or identifying and replacing faulty transmission control modules, attention to detail is paramount. Proper resolution helps maintain the vehicle’s performance and reliability, especially in terms of clutch operation and gear shifting.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko