A faulty stop lamp switch, which is the most common cause and often wears internally or sticks.; A misadjusted stop lamp switch that does not fully change state when the pedal moves.; Corroded, loose, or damaged electrical connectors at the switch or at the module.; A broken, chafed, or shorted wire in the stop lamp switch circuit.; A blown fuse that supplies power to the stop lamp switch circuit.; A failed brake pedal position sensor on vehicles that use a separate sensor rather than a simple switch.; A software or internal fault in the ABS module or body control module, which is rare but possible.

DTC codes / C02xx · Brakes, steering and suspension / C0205

C0205Stop Lamp Switch Circuit

Q: What does code C0205 mean?

Stop Lamp Switch Circuit. This code means the computer that monitors the antilock braking system (ABS) or body control module has detected an implausible signal on the stop lamp switch circuit, which is the electrical path from the brake pedal switch to the module. The module expects a specific voltage pattern when the brake pedal is pressed and released, and it has seen a value outside that expected range for a set period of time.

This code means the computer that monitors the antilock braking system (ABS) or body control module has detected an implausible signal on the stop lamp switch circuit, which is the electrical path from the brake pedal switch to the module. The module expects a specific voltage pattern when the brake pedal is pressed and released, and it has seen a value outside that expected range for a set period of time.

SystemChassis

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaBrakes, steering and suspension

Symptoms you may notice

The antilock brake system (ABS) warning light or brake system warning light is illuminated on the dashboard.
The brake lights may stay on continuously or fail to illuminate when the pedal is pressed.
Cruise control may fail to engage or may disengage unexpectedly when the brake pedal is touched.
The transmission may be difficult to shift out of park because the brake pedal position signal is missing.
Traction control or stability control may be disabled and show a warning message.
Often no symptoms besides the warning light, with normal braking performance.

Common causes, most likely first

A faulty stop lamp switch, which is the most common cause and often wears internally or sticks.
A misadjusted stop lamp switch that does not fully change state when the pedal moves.
Corroded, loose, or damaged electrical connectors at the switch or at the module.
A broken, chafed, or shorted wire in the stop lamp switch circuit.
A blown fuse that supplies power to the stop lamp switch circuit.
A failed brake pedal position sensor on vehicles that use a separate sensor rather than a simple switch.
A software or internal fault in the ABS module or body control module, which is rare but possible.

How to diagnose and fix it

Check the brake lights with a helper to see if they work normally, stay on, or never come on, which narrows the fault quickly.
Inspect the stop lamp switch and its connector for looseness, corrosion, or physical damage, and verify the switch plunger moves freely.
Test the switch with a multimeter to confirm it opens and closes the circuit as the pedal is pressed and released.
Check the fuse that feeds the stop lamp switch circuit and replace it if blown, then recheck for the code.
Inspect the wiring harness between the switch and the ABS module for chafing, pinched wires, or poor grounds.
Clear the code and test-drive the vehicle to see if it returns, which confirms whether the repair was effective.
If the circuit tests good, follow the manufacturer's diagnostic flow for the ABS module or body control module before replacing any module.

Stop lamp switch faults that fool technicians

A stop lamp switch can test fine with a multimeter at rest but fail intermittently when the pedal is pressed, so a wiggle test and a live data scan are more reliable than a static check.
On many vehicles the stop lamp switch has multiple internal contacts, and only one set may fail, so the brake lights can work while the ABS module still sees an implausible signal.
Aftermarket LED brake light bulbs or trailer wiring taps can back-feed the stop lamp circuit and set this code even though the switch itself is healthy.
A weak or failing battery can cause the module to log this code during cranking because the voltage drop mimics an implausible switch signal.
The code can be set by a brake pedal that does not fully return because of a binding pedal pivot or a worn return spring, which is easy to overlook.

Can I keep driving with C0205?

The vehicle remains safe to drive in most cases because the base hydraulic brakes still work, but you should avoid relying on cruise control and be aware that the ABS and stability control may be disabled. Have the fault diagnosed soon, especially if the brake lights are not working, because that is a safety and legal issue.

Tools that help

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