P0805

Clutch Position Sensor Circuit

P0805 is a generic OBD-II powertrain diagnostic trouble code: Clutch Position Sensor Circuit. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0805
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P0805 means

P0805 is a generic code stored when the powertrain control module (PCM) or transmission control module (PCM/TCM) sees a voltage or resistance in the clutch position sensor circuit that falls outside the expected range. It applies to vehicles with a manual gearbox, and to automated manual and dual-clutch transmissions that use a clutch position feedback device. The sensor reports how far the clutch pedal, or on automated systems the clutch actuator, has travelled. Depending on the vehicle it may be a simple switch, a two-stage switch or a potentiometer giving a continuously variable output.

The module uses that clutch information for several jobs. On a conventional manual it enables the starter only with the clutch depressed, cancels cruise control the moment you touch the pedal, and adjusts idle and fuel cut-off during gear changes so the engine does not stumble or flare. On automated manual and dual-clutch gearboxes the signal is far more central: the transmission module uses clutch position feedback to control engagement point, creep and launch. The code sets when the reported value is implausible, for example stuck at one end of its range or contradicting engine and road speed.

Consequences therefore vary by design. A manual car may show only a check engine light plus lost cruise control and odd idle behaviour, while an automated manual or dual-clutch car can lose smooth engagement and may refuse to move. Start diagnosis with wiring, connector and adjustment before condemning the sensor.

Common causes

Most-frequently reported root causes when P0805 is logged.

  • 1
    Failed clutch position sensor or switch, either open, shorted internally or worn in one part of its travel.
  • 2
    Damaged, chafed or broken wiring in the pedal area or the harness run to the control module.
  • 3
    Corroded, loose or water-damaged connector at the sensor, which is common in a footwell that has been wet.
  • 4
    Sensor or switch out of adjustment, misaligned, or knocked loose from its bracket.
  • 5
    Worn or broken pedal linkage, bracket or clutch pedal bushing so the pedal no longer moves the sensor through its full range.
  • 6
    On automated manual and dual-clutch gearboxes, a failing clutch actuator or its internal position sensor.
  • 7
    Poor power or ground supply to the sensor, or a shared ground shorted by another circuit.
  • 8
    A faulty control module input circuit, which is the least likely and should be confirmed last.

Symptoms drivers notice

Check engine light on, sometimes with no obvious change in how the car drives.
The engine cranks without the clutch pedal pressed, or refuses to crank even with it fully down.
Cruise control will not engage, or does not cancel when the clutch is pressed.
Idle speed hangs high or dips too low when the clutch is depressed during gear changes.
On automated manual or dual-clutch cars, jerky take-up, slipping engagement, or the car will not pull away at all.
Occasional stalling when coming to a stop or during a shift.

How to diagnose P0805

A typical diagnostic flow when this code is present.

  1. 1
    Read all stored codes and freeze-frame data, and check for related clutch, cruise control or starter circuit codes that share the same wiring.
  2. 2
    Watch the clutch position or clutch switch value in live data while an assistant slowly presses and releases the pedal, and note any dead spots, jumps or values that never change.
  3. 3
    Inspect the connector and harness at the sensor and along the pedal-box run for corrosion, chafing on the pedal assembly, and pushed-back terminals, since footwell wiring is easily damaged.
  4. 4
    Verify that the sensor or switch is correctly mounted, aligned and adjusted, and that the pedal, bracket and linkage move it through its full intended travel without free play.
  5. 5
    Confirm sensor reference voltage and ground at the connector with the ignition on, and check the ground for excessive voltage drop.
  6. 6
    Measure the sensor's output as the pedal is moved and compare it against the manufacturer's specification for that vehicle, wiggle-testing the harness to expose intermittent breaks.
  7. 7
    Only if supply, ground, wiring, adjustment and sensor output all check out should you back-probe the module connector and consider the module input itself.

Related powertrain codes

Frequently asked questions

Can I keep driving with P0805?

On a conventional manual it is usually drivable, though you may lose cruise control and notice odd idle behaviour, and the car might crank without the clutch pressed, which is a safety risk. On an automated manual or dual-clutch car it can prevent smooth engagement or leave you stranded, so treat it as urgent.

Will P0805 fail an emissions test?

Yes. It is a stored powertrain code and the check engine light is on, which fails an OBD-II inspection even though the fault itself has little to do with tailpipe emissions.

Is this expensive to fix?

Usually one of the cheaper faults. Clutch position switches and sensors are inexpensive and often accessible at the pedal box, and adjustment or a wiring repair may be all that is needed. It gets costly only when the clutch actuator on an automated gearbox is at fault.

Why does my car now start without the clutch pressed?

On many manuals the same clutch position signal enables the starter. If the module reads the pedal as permanently depressed, the interlock is effectively bypassed. Always leave the car in neutral with the handbrake on until this is repaired, because it can start in gear and lurch forward.

Disabling P0805 in software

RaceTune can permanently disable P0805 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

ECU families we can disable P0805 on

We hold the DaVinci A2L disable definitions for these families, so the exact P0805 path and mask addresses are mapped. verified marks a confirmed disable definition. We support many more — upload your file and our identifier will match it automatically.

  • Bosch EDC17C60 verified

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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