P0704: Clutch Switch Input Circuit (Meaning, Causes, Fixes)
What P0704 means
On a manual transmission, a switch on the clutch pedal tells the powertrain control module (PCM) whether the pedal is pressed. OBD-Codes.com explains that its main job is safety: it interrupts the starter signal so the engine can't be cranked unless the clutch pedal is pushed down, and the PCM and other modules also use it for engine control, automated braking, hill-hold and stop-start. It describes P0704 as a generic code (it lists Ford, Honda, Mazda, Mercedes and VW among examples) that sets when the PCM detects a malfunction in the clutch switch input circuit, and says it applies only to vehicles with manual transmissions. RepairPal defines P0704 as Clutch Switch Input Circuit, set when the PCM detects an incorrect signal from the clutch position sensor. The sources differ in detail: OBD-Codes.com calls it a clutch switch and lists several symptoms (hard starting, idle and fuel economy changes, traction control off), while RepairPal calls the part a clutch position sensor and lists only that the engine may not start. OBD-Codes.com also lists a worn clutch pedal lever or bushing as a cause, which RepairPal doesn't mention. Related codes are P0700 (transmission control system MIL request), P0703 (brake switch B circuit) and P0705 (transmission range sensor A circuit).
Severity: can I keep driving?
Stop and fix promptly
Get it fixed soon. OBD-Codes.com says P0704 should be treated as urgent because drivability, safety and traction control functions may be interrupted while it is stored. RepairPal also rates P0704 Urgent. Since the clutch switch is the safety interlock that keeps the engine from starting in gear, always hold the clutch down and keep your foot on the brake when starting the car until it's fixed.
Common symptoms
- Engine won't start, or starts only some of the time (both sources)
- Lower fuel economy (OBD-Codes.com)
- Engine idles too high (OBD-Codes.com)
- Traction control disabled (OBD-Codes.com)
- Some safety functions, such as hill-hold or stop-start, may be disabled on some models (OBD-Codes.com)
Likely causes
Roughly most to least common, based on the sources below. Your vehicle may differ.
- Defective clutch switch or clutch position sensor (both sources)
- Worn clutch pedal lever or clutch lever bushing, which OBD-Codes.com says is often misdiagnosed as a bad switch (OBD-Codes.com)
- Open or shorted wiring or connectors in the clutch switch circuit (both sources)
- Blown fuse or burnt fusible link (OBD-Codes.com)
- Faulty PCM or a PCM programming error (both sources)
Diagnostic steps you can do
Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.
- Look at the clutch switch at the top of the clutch pedal, its connector and wiring, and check the pedal arm and pivot bushing for play or wear.
- Test the fuses for the circuit, including with the clutch pedal pressed. OBD-Codes.com notes a fuse can look fine but fail once the circuit is under load.
- Load test the battery and check the battery cables and alternator output, as OBD-Codes.com recommends.
- Read and write down all stored codes and freeze frame data, clear them, and test drive to see if P0704 comes right back.
- With a digital volt/ohmmeter and a service manual, check for battery voltage at the switch input, then at the switch output with the pedal pressed. No output voltage points to a bad or misadjusted switch, per OBD-Codes.com. Some vehicles have more than one clutch switch.
Typical fixes
- Replace or readjust the clutch switch
- Replace a worn clutch pedal bushing or pivot lever
- Replace a blown fuse and find what caused it to blow
- Repair open or shorted wiring or connectors between the clutch switch and the PCM
- Reprogram or replace the PCM only after the switch, pedal, fuses and wiring check out
Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.
🛠 When to call a pro
- The car won't start even with the clutch pedal fully pressed
- The code comes back after replacing the switch
- Traction control or hill-hold stays disabled
- You don't have a meter or wiring diagram to trace the circuit
Where to buy
Plain search links. Always match parts to your exact year, make, model and engine.
FAQs
Is P0704 the clutch switch?
Usually. Both sources list a bad clutch switch (RepairPal calls it the clutch position sensor) as a cause, but OBD-Codes.com warns a worn clutch pedal bushing or pivot arm is often mistaken for a bad switch, so check those and the fuses too.
Why won't my car start with P0704?
The clutch switch tells the starter circuit the pedal is down. If the PCM or starter circuit doesn't get that signal, the engine may not crank, which both sources list as a symptom.
Can P0704 show up on an automatic?
OBD-Codes.com says P0704 applies only to vehicles with manual transmissions. If an automatic shows it, have the code and vehicle-specific definition checked with a good scan tool.
How much does it cost to fix P0704?
Neither source gives a repair cost. It can be as simple as a fuse or switch adjustment, so get a diagnosis or written estimate before replacing parts.
Sources
Last reviewed 2026-10-25. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.