One of the level control solenoid valves reports an electrical fault. The corresponding axle cannot be levelled.
Medium severity. Can I keep driving?Drive slowly and avoid long trips if the car is sitting low or behaving strangely.
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Most likely causes
- Solenoid coil open
- Connector water damage
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
What each character of C0840 means
- C: Chassis
- 0: Generic code: same on every make
- 8: Subsystem depends on the code range
- 40: Specific fault in that system
Frequently asked questions
Can I keep driving with code C0840?
Drive slowly and avoid long trips if the car is sitting low or behaving strangely.
What causes code C0840?
The most common causes are: solenoid coil open; connector water damage.
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.