U0100 on Ford Focus
Lost Communication With ECM/PCM A
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Ford Focus context without treating complaints as confirmed diagnoses.
Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).
- SAE J2012 Diagnostic Trouble Code Definitions — Generic diagnostic trouble code definition reference for U0100.
- NHTSA recalls, complaints, and manufacturer communications — Used to check public owner complaint context, recall status, and safety-related manufacturer communications by VIN or vehicle.
Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.
What U0100 Means on Your Ford Focus
U0100 is a diagnostic trouble code indicating: Lost Communication With ECM/PCM A. This code relates to the network communication system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.
Real Ford Focus Owner Reports
Source: NHTSA Complaints Database
"*ongoing *please see original complaint # 10473215 *clutch replaced twice and trans reprogrammed 4/5 times (within 35, 000) *now car not starting- 4 times in 2 months."
"The contact owns a 2014 Ford Focus. The contact stated that on numerous occasions while shifted into reverse(R), the vehicle failed to respond. The contact also stated that while shifted into reverse(R), the RPM increased and the engine revved while the brake pedal was depressed."
"Some 2011-2016 fiesta and 2012-2016 focus vehicles equipped with a dps6 transmission may exhibit intermittent concerns of loss of transmission engagement while driving, intermittent no syart or loss of power. these symptoms are usually accompanied by an illuminated check engine lamp."
All reports filed by vehicle owners directly with the U.S. Department of Transportation.
📊 Complaint Trend by Model Year
Common Causes on Ford Focus
Based on NHTSA complaint component analysis for this vehicle.
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
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2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
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3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.