Code Definition

C1851 — Air Suspension Warning Lamp Circuit Open

System: Chassis  |  Type: Manufacturer-Specific  |  Make: Ford

About C1851

C1851 is a manufacturer-specific chassis diagnostic trouble code recorded for Ford vehicles. It belongs to the C-prefix family of codes, which covers chassis, braking, steering, suspension, or stability-control faults.

When C1851 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit.

Scanning & clearing: Chassis (C) codes are stored in the ABS, traction control, or stability-control modules. An enhanced or OEM-level scan tool is usually required to read and clear them.

C1851 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Ford air suspension control module drives the air suspension warning lamp and monitors the lamp output circuit so it can confirm the lamp will illuminate when a fault needs to be shown. DTC C1851 sets specifically when the module detects an open circuit in the warning lamp output, meaning current cannot flow through the lamp and its wiring. This is most commonly caused by a blown bulb, a broken or disconnected wire, or corroded terminals that interrupt the circuit. When this code is set the air suspension warning lamp will not illuminate on demand, so the driver may be unaware of an active...

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