OBD-II trouble code
P0805: Clutch Position Sensor Circuit
The module has lost a usable signal from the sensor that reports how far the clutch pedal has travelled. The word that matters in the title is sensor — this is a continuous position measurement, not the simple on/off clutch switch.
Quick facts
- System
- Powertrain
- Category
- Transmission / Shift Control
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $90 – $600
- DIY difficulty
- Intermediate DIY
What does P0805 mean?
A clutch switch answers one question: is the pedal down or is it not? A clutch position sensor answers a harder one: exactly where in its travel is the pedal right now, expressed as a continuous value from fully released to fully depressed. P0805 belongs to the second device, and confusing the two is the most common way this code gets misdiagnosed. A vehicle can have both fitted, on the same bracket, wired to the same module.
The reason a manufacturer pays for the more expensive part is that some strategies need to know not just that the clutch is moving but *how far along* it is. Stop-start systems restart the engine at a specific point in the pedal's downward travel, early enough that the engine is running by the time the driver wants drive but late enough that it does not restart every time somebody rests a foot. Hill-hold releases the brakes as the pedal comes back through the bite point, which the module can only find if it can see the whole sweep. Anti-stall torque intervention needs to know how fast the pedal is being released, which is a rate calculated from position. And on automated manuals and dual-clutch transmissions the position signal is closed-loop feedback for an actuator that operates the clutch with no driver pedal involved at all.
That is why P0805 is not evenly distributed across the fleet. It is a code you see on stop-start manuals, on European diesels with hill-hold, and on automated manual and DCT gearboxes — populations where the sensor is doing continuous control work. On a plain manual with a pedal switch and nothing clever behind it, this code will generally not be supported at all.
P0805 is the general or parent member of a family. When the module can classify the fault more precisely it will store one of the specific members instead: out of expected range, too low, too high, or intermittent. Getting P0805 by itself usually means the input failed in a way the classifier could not put in a box — no signal at all, a reference that vanished, or a signal that fails several tests at once.
The physical sensor comes in three forms and the form decides how you test it. A rotary potentiometer on the pedal pivot has a wiper on a resistive track and can develop a dead spot partway through its sweep, so it is tested by watching for a dropout while moving the pedal slowly. A linear plunger design is the same idea in a straight line. A Hall-effect design reads a magnet on the pedal arm and has no wiper to wear, so it does not produce dropouts — it produces steps, offsets or complete loss. Sweeping a Hall sensor looking for a dead spot will find nothing and prove nothing.
Common causes
- Failed clutch position sensor, either an open element or a wiper that has lost contact with its track
- Loss of the 5-volt reference or the sensor ground at the connector
- Corroded connector in the footwell, which sits at the lowest point in the cabin and collects moisture carried in on shoes
- Chafed wiring where the pedal-box loom passes through the bulkhead grommet and flexes with pedal movement
- Sensor knocked out of position or its bracket bent during pedal box, hydraulic or carpet work
- Magnet displaced or debris between magnet and sensor face on Hall-effect designs
- Aftermarket alarm, remote start or immobiliser wiring spliced into the clutch circuit
- Water ingress from a leaking bulkhead seal or heater matrix soaking the connector
- Failed module input, which is uncommon and should only be concluded after the sensor, reference, ground and harness have all been proven
Symptoms
- Check engine light with the car otherwise driving normally
- Stop-start stops working, or restarts the engine at the wrong point in the pedal travel
- Hill-hold releases too early or does not hold at all
- Idle dipping or flaring during gear changes as the module loses track of the pedal
- Cruise control unavailable or cancelling on its own
- On automated manual and dual-clutch vehicles, hesitant or jerky take-up, or a refusal to select a gear
- Harsh engagement from rest because the anti-stall strategy has been disabled
- Additional sensor codes stored at the same time, pointing at a shared reference rather than at this sensor
Diagnostic steps
- 1.Establish which device you are dealing with before touching anything. Look at the sensor: three wires and a continuous reading on the scan tool is a position sensor; two wires and a state that flips between on and off is a switch, and a switch fault is P0704, not this code.
- 2.Watch the clutch position value on a scan tool while an assistant depresses and releases the pedal very slowly. A healthy sensor sweeps smoothly through its whole range with no jumps, no flat spots and no sudden return to zero.
- 3.Note the reading at both ends of travel and write them down. Released and fully depressed values that sit well inside the specified endpoints suggest a mechanical problem with pedal travel rather than an electrical one.
- 4.Check whether other sensors have set codes at the same time. Several unrelated sensors failing together points at a shorted or lost 5-volt reference shared between them, not at the clutch sensor itself.
- 5.Back-probe the connector with the circuit live and confirm reference voltage and a good ground. Test the ground with a voltage-drop measurement, because a corroded ground can read a few ohms on a meter and still collapse under load.
- 6.Inspect the connector for the green corrosion and spread terminals typical of a footwell location, and check for water tracking down the loom from a bulkhead or heater leak.
- 7.Flex the harness where it passes through the bulkhead while watching the live value. This is the section that moves with the pedal and it is where chafes form.
- 8.On Hall-effect designs, check that the magnet is still attached to the pedal arm and that nothing metallic has collected on the sensor face. There is no wiper to fail on these, so a mechanical cause is more likely than a worn element.
- 9.If the sensor is replaced, carry out the manufacturer's clutch position adaptation or relearn. Many vehicles will store a range or performance fault immediately if the new sensor's endpoints are never taught to the module.
Repair cost
$90 – $600
The sensor itself is typically $30 to $220 depending on whether it is a simple potentiometer or an integrated pedal-mounted assembly, and labour is usually 0.4 to 1.8 hours, so $110 to $450 fitted at a shop. Repairing a corroded connector or a chafed section of harness comes in around $120 to $300. Diagnosis is $90 to $150 and is worth paying for on this code specifically, because the sensor and the switch look similar in the footwell and replacing the wrong one is a common and entirely avoidable outcome. On automated manual and dual-clutch vehicles the sensor may be integrated into the actuator assembly, which pushes the total toward the top of the range and can exceed it.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with clutch position sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.