Engine control module recently replaced, reprogrammed or reset without the correct variant or configuration being set; Variant or configuration data in the module corrupted or incorrectly written; Wrong or non-original module fitted for the vehicle's engine, transmission or market specification; Wiring or connector fault on a circuit the module uses to identify the variant (for example a coding or strapping input), depending on model; Low battery voltage or supply and earth problems during module programming or start-up, leaving incomplete data; Internal fault in the engine control module.

P1187

Variant Selection.

Ford
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
1: AreaFuel and air metering
87: FaultThe specific fault in that area

What it means

On Ford and Lincoln-Mercury vehicles P1187 is listed as 'Variant Selection'. It points to the engine control module's variant or configuration data not being valid or not matching the vehicle. The exact test and the data checked vary by model, engine and year, so confirm against manufacturer information for the specific vehicle.

Symptoms

Engine warning light on
Possible poor running, hesitation or reduced performance if the module is using default strategies
Rough idle or unusual idle speed on some applications
Poor fuel economy
Possible hard starting or no start after a module has been replaced or reprogrammed

Possible causes

Engine control module recently replaced, reprogrammed or reset without the correct variant or configuration being setlikely
Variant or configuration data in the module corrupted or incorrectly writtenpossible
Wrong or non-original module fitted for the vehicle's engine, transmission or market specificationpossible
Wiring or connector fault on a circuit the module uses to identify the variant (for example a coding or strapping input), depending on modelpossible
Low battery voltage or supply and earth problems during module programming or start-up, leaving incomplete datapossible
Internal fault in the engine control modulerare

How to diagnose

Read all stored and pending codes plus freeze frame data, and note whether other module or communication codes are present.
Ask about recent history: module replacement, software update, battery disconnection or previous repairs.
Check battery condition and charging voltage, as low voltage can corrupt module data.
Inspect the module connectors, wiring, supply and earth connections for damage, corrosion, water ingress or poor pin tension.
Compare the module part number and software level with the vehicle's specification for its engine, transmission and market.
Look up manufacturer information for the vehicle to see which inputs or configuration data the variant selection relies on.
Clear the code and road test, then recheck to see whether it returns immediately or only under certain conditions.

How to fix

Set the correct variant or configuration for the vehicle using the manufacturer's procedure if the module was replaced or not configured.
Repair any wiring, connector, supply or earth faults found on the module or its identification inputs.
Replace the module with the correct specification unit if the wrong one is fitted, then configure it properly.
Restore a healthy battery and charging system, then repeat the configuration if the data was corrupted.
Replace the engine control module only if testing confirms an internal fault, then configure it for the vehicle.

Can I keep driving?

Medium severity

The car may be driveable if it runs normally, but have it checked soon because the module could be using default settings that affect performance and economy. If it runs badly, stalls or will not start, limit driving and get it diagnosed promptly.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.