P1801

What it means

P1801 is a manufacturer-specific code, and for this definition it means the control unit has detected an open circuit in the clutch interlock (clutch pedal position) safety switch circuit. The switch tells the control unit when the clutch pedal is pressed, which is normally needed to allow starting and for some driving functions. The code sets when the signal is missing or out of range, for example no voltage or a broken connection. Other makes may use P1801 for something different, so confirm the definition for the exact vehicle.

Symptoms

• Engine cranks slowly or not at all when the key is turned or start button pressed
• Engine starts only with the clutch pedal in a particular position, or not at all
• Cruise control not working
• Start-stop system unavailable or behaving oddly
• Malfunction warning light on
• Intermittent starting problems that come and go

Possible causes

• Faulty or worn clutch interlock switchlikely
• Damaged, corroded or loose connector at the switchlikely
• Open circuit or chafed wiring between the switch and the control unitlikely
• Switch out of adjustment or its mounting or pedal bracket damaged or wornpossible
• Blown fuse or loss of supply or earth to the switch circuitpossible
• Fault inside the control unit or an outdated calibration, where the manufacturer lists it as a known issuerare

How to diagnose

1. Read all stored and pending codes and note the freeze frame data, including whether the fault is current or intermittent
2. Check for related codes or other no-start and cruise control faults that point to a shared supply or earth problem
3. Inspect the clutch pedal switch, its mounting and its connector for damage, looseness, moisture and corrosion
4. Watch the clutch switch state in live data while pressing and releasing the pedal, and check it changes cleanly
5. Check the relevant fuse and the switch supply and earth against the wiring diagram for the model
6. Test the switch with a multimeter for continuity and correct operation as the pedal moves, following the manufacturer's procedure
7. Check wiring continuity between the switch and the control unit, and wiggle the harness while monitoring for dropouts
8. Check for manufacturer service bulletins or calibration updates for the specific model and engine

How to fix

• Repair or replace damaged wiring and terminals in the switch circuit
• Clean, secure or replace a corroded or loose connector
• Replace the clutch interlock switch if it fails testing
• Adjust or repair the switch mounting and pedal bracket so the switch operates correctly
• Replace a blown fuse after finding and fixing the reason it failed
• Apply a manufacturer calibration update only if a bulletin confirms it applies to this fault

Can I keep driving?

This code for other makes

• P1801BuickPerformance Selector Switch Failure
• P1801CadillacPerformance Selector Switch Failure
• P1801ChevroletPerformance Selector Switch Failure
• P1801GMPerformance Selector Switch Failure
• P1801GMCPerformance Selector Switch Failure
• P1801OldsmobilePerformance Selector Switch Failure
• P1801SaturnPerformance Selector Switch Failure

Nearby codes

• P1800OtherTransmission Clutch Interlock Safety Switch Circuit Failure
• P1802OtherTransmission Clutch Interlock Safety Switch Short Circuit To Battery