P0806: Clutch Position Sensor Circuit Range/Performance Powertrain Code

P0806: Clutch Position Sensor Circuit Range/Performance (Powertrain Code)

Overview and definition

• What the code means: P0806 indicates a problem with the clutch position sensor (CPS) circuit, specifically that the sensor's range or the performance of its signal is out of expected parameters. In other words, the PCM/TCM is receiving a CPS signal that is out of range, erratic, or not matching the pedal/clutch position input in the expected way. This is categorized under powertrain codes and is used by the transmission control logic to verify clutch status and engagement readiness. Sources describe P0806 as a CPS circuit range/performance issue within the OBD-II framework.

• System impact: This is a transmission-related (powertrain) diagnostic, typically associated with manual- or clutch-reliant controls. The CPS is part of feeding the PCM/TCM with the clutch position input, which can affect starting, idle behavior, and transmission shifting logic if the signal is invalid or out of range.

Symptoms

• Check Engine Light (CEL/ MIL) illuminated with P0806 in the scan tool data.
• Transmission shifting problems: hard shifts, delayed engagement, missed shifts, or non-linear shift behavior.
• Starting or clutch engagement anomalies in manual-transmission vehicles: vehicle may not start or may show erratic clutch-related start conditions if the CPS signal is not indicating proper clutch engagement.
• Inconsistent or fluctuating CPS readings on live data, or a lack of expected pedal/clutch position correlation.

Probable Causes

• Clutch Position Sensor failure or internal circuit fault: highest probability (roughly 40-50%). The sensor itself is a common fault source for range/performance issues.
• Wiring harness damage, connector problems, or poor connections in CPS circuits: 20-30%. Exposure to heat, vibration, and oil/grease can damage insulation or grounds, creating intermittent or out-of-range signals.
• PCM/TCM software or input fault (control module interpretation, calibration, or re-learn needs): 10-15%.
• Mechanical issues related to the clutch assembly or sensor mounting (e.g., sensor misalignment, mounting looseness, hydraulic system interaction): 5-10%.
• Sensor calibration or re-learn requirements after replacement or electrical work: 5%.
  Note: These probability estimates are provided to guide diagnostics in the absence of explicit NHTSA complaint frequency data . They reflect typical field experience with CPS-related trouble codes and the likelihood of CPS/wiring issues being involved.

Diagnostic Approach

1) Confirm the code and collect data

• Use a capable scan tool to confirm P0806 is stored, along with freeze-frame data. Note any related codes (e.g., other CPS signals, transmission-related codes). This helps determine if the issue is isolated to CPS or part of a broader transmission fault.

2) Visual inspection and basic electrical checks

• Inspect the CPS connector and wiring for damage, corrosion, oil/grease contamination, or loose/unplugged connections. Check for harness abrasion or grounded circuits near moving parts. Inspect the clutch pedal switch as applicable to the vehicle (to confirm there isn't a separate pedal-switch issue masking CPS symptoms).
• Check for moisture intrusion or signs of heat damage in the CPS harness and at the connector. Any corrosion or damaged insulation should be addressed prior to functional testing.

3) Validate baseline with live data

• With the engine running (if allowed by the vehicle), monitor the CPS signal in live data. Compare the CPS reading to Actual clutch position (pedal or mechanical position) to assess correlation and range. A significant mismatch or signal out of expected range supports a CPS or wiring fault.

4) Inspect ancillary systems

• Look for related transmission inputs or control signals that could influence CPS interpretation (e.g., TCM/PCM data, other transmission fault codes). Be aware that sometimes a CPS fault can be accompanied by other powertrain or transmission codes.

5) Functional testing of the CPS

• If the CPS is located in the transmission or near the clutch assembly, test with a multimeter or scope as appropriate:
  • Verify continuity and resistance/voltage behavior across the sensor circuit per the vehicle's service information.
  • Check for intermittent signal loss or spikes. If a schematic shows a potentiometer-style CPS, verify that signal transitions are smooth and within the expected range during clutch engagement/disengagement.
  • Confirm that supply voltage, ground, and signal lines are within expected ranges when the clutch is manipulated.

6) Corrective actions based on findings

• If the CPS is confirmed faulty or signal is consistently out of range:
  • Replace the clutch position sensor (CPS) and any damaged wiring or connectors.
  • Reconnect and reseat all related harnesses and perform any required sensor re-learn or calibration procedure as specified by the vehicle's service information.
• If wiring/connectors are the fault:
  • Repair or replace damaged wiring, fix connectors, and ensure proper routing to avoid future wear.
• If the PCM/TCM requires software or calibration updates:
  • Update or reflash the control module if supported by the vehicle manufacturer, and perform any required relearn procedure.

7) After repair verification

• Clear codes and perform a test drive under various driving conditions to verify the issue is resolved. Confirm CPS signals in live data match clutch position and that no related codes reappear.

Manufacturer Notes

• The clutch position sensor is typically part of the transmission assembly or the clutch actuation system. Depending on the make/model, it may be a potentiometer-type sensor, a Hall-effect sensor, or a similar device whose output travels to the PCM/TCM. The general diagnostic approach remains the same: verify signal range, check wiring, inspect connectors, and replace faulty CPS if needed. The definition of P0806 as CPS circuit range/performance comes from the open-source code description and is consistent with the OBD-II powertrain code framework described by Wikipedia.

Repair Options

• CPS replacement: primary fix for confirmed CPS fault. After replacement, perform any required relearn/calibration and verify live data correlation.
• Wiring/connector repair: fix shorts, opens, or grounding issues in the CPS circuit. Re-test signal range and continuity after repair.
• PCM/TCM software update or reflash: if indicated by vehicle manufacturer; re-test to ensure the code does not return.
• Post-repair test drive: confirm no additional codes and that CPS signal aligns with actual clutch position under a range of operating conditions (idle, acceleration, gear changes).

Safety Considerations

• Disconnect battery power when performing electrical repairs near the CPS wiring, if service procedures require it.
• Follow vehicle-specific service information for any required depressurization of hydraulic systems, and avoid contact with hot components.
• Ensure vehicle is securely supported if work is performed with the transmission or clutch area exposed to avoid injury.

This diagnostic guide was generated using verified reference data:

• Wikipedia Technical Articles: OBD-II
• Open-Source OBD2 Data: N/A (MIT)

Content synthesized from these sources to provide accurate, real-world diagnostic guidance.

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