Chafed or pinched starter interlock signal wire shorting to ground in the engine bay or under the dash; Faulty clutch pedal position switch or transmission range sensor internally shorted to ground; Corroded or water-intruded connector on the interlock circuit, especially at the transmission or pedal assembly; Failed starter interlock relay with internal short to ground; Damaged wiring harness from rodent damage or previous repair work; Faulty body control module or gateway module not recognizing the interlock signal correctly

DTC codes / Volkswagen codes / P1724

P1724 · VolkswagenStarter Interlock Circuit Short To Ground

Q: What does code P1724 mean?

Starter Interlock Circuit Short To Ground. P1724 on Volkswagen vehicles means the starter interlock circuit has been detected as shorted to ground, which the control module sees as an unexpected low-voltage condition on the interlock signal wire. The starter interlock prevents the engine from cranking unless the transmission is in Park or Neutral or the clutch pedal is depressed, so this fault can disable cranking entirely.

P1724 on Volkswagen vehicles means the starter interlock circuit has been detected as shorted to ground, which the control module sees as an unexpected low-voltage condition on the interlock signal wire. The starter interlock prevents the engine from cranking unless the transmission is in Park or Neutral or the clutch pedal is depressed, so this fault can disable cranking entirely.

SystemPowertrain

Code typeVolkswagen specific

SeverityHigh

Fix difficultyIntermediate

AreaTransmission

Symptoms you may notice

Engine will not crank when the key is turned or the start button is pressed
Starter may crank in gear or without the clutch pedal depressed, creating a safety hazard
Intermittent no-crank condition that comes and goes with vibration or moisture
Warning light or message on the instrument cluster related to starting system or transmission
Often no symptoms besides the warning light if the short is intermittent and does not currently prevent cranking

Common causes, most likely first

Chafed or pinched starter interlock signal wire shorting to ground in the engine bay or under the dash
Faulty clutch pedal position switch or transmission range sensor internally shorted to ground
Corroded or water-intruded connector on the interlock circuit, especially at the transmission or pedal assembly
Failed starter interlock relay with internal short to ground
Damaged wiring harness from rodent damage or previous repair work
Faulty body control module or gateway module not recognizing the interlock signal correctly

How to diagnose and fix it

Scan all modules for stored codes and check live data for the starter interlock input status while pressing the clutch or moving the selector
Inspect the clutch pedal switch or transmission range sensor connector for corrosion, water intrusion, and loose pins
Disconnect the interlock circuit at both ends and measure resistance to ground on the signal wire to confirm a short
Visually trace the harness from the pedal or transmission to the control module for chafing, pinching, or rodent damage
Test the starter interlock relay by swapping with a known-good relay of the same part number and rechecking the code
Repair or replace the damaged section of wiring, then clear the code and verify cranking in Park and Neutral or with the clutch pedal depressed
If the short persists after wiring and switch checks, test the control module input circuit and replace the module only after confirming all external circuits are sound

What a shorted interlock wire really means

A short to ground on the interlock circuit does not always mean the wire is rubbed through; a failed clutch pedal switch or range sensor can pull the signal low internally and set the same code.
On many Volkswagen models the starter interlock signal passes through the body control module or gateway, so a water-damaged module or corroded connector far from the starter can be the real cause.
Intermittent P1724 codes often appear after heavy rain or car washing when moisture enters a connector on the transmission or pedal assembly, so check for water tracks before replacing parts.
Technicians sometimes replace the starter or ignition switch when the engine will not crank, but P1724 points to the interlock circuit, and the starter may be perfectly functional.
A short to ground can be caused by a previous repair that pinched the harness behind the dash or near the pedal bracket, so inspect recent work areas first.

Can I keep driving with P1724?

Do not continue driving if the engine will not crank or if the starter engages in gear, because the interlock safety function is compromised. If the vehicle still starts and drives normally with only a warning light, drive directly to a repair shop and avoid leaving the vehicle in a position where an unexpected crank could occur.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Volkswagen vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.