How is fault code P0805 fixed?

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Pull every stored and pending code first. P0805 sitting alongside body or start-system codes points you straight at the interlock circuit rather than the gearbox itself 2. Get up under the dash to the clutch switch, give it a wiggle and check it's clipped in and aligned. A switch that's drooped off its bracket will throw this code and is a two-minute fix 3. Unplug the connector and look for green corrosion, spread pins or a loose terminal, clean it up and reseat it before you go any further 4. With the multimeter, check you've got the proper supply voltage at the switch with the ignition on, usually a 5V reference or battery feed depending on the car 5. Press the pedal and watch the output change as the switch operates. No change means a dead switch 6. If supply, signal and connections all check out, go through the wiring back to the ECU for an open or a short, then and only then start thinking about the module

Clutch Position Sensor Circuit Malfunction

Jump to the fix

Severity

High

Can I keep driving?

Avoid extended driving; visit a service soon.

First step

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Pull every stored and pending code first. P0805 sitting alongside body or start-system codes points you straight at the interlock circuit rather than the gearbox itself 2. Get up under the dash to the clutch switch, give it a wiggle and check it's clipped in and aligned.

PPowertrain
0Generic code
8Transmission
05Sequence number

What does it 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.

Symptoms

Likely causes

How to fix it

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All Fault Codes

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This information follows the generic OBD-II definition and does not replace a vehicle-specific diagnosis. The severity rating is rule-based; an authorised diagnostic reading is required for a definitive answer.