Reference meaning
What does this code mean?
The wording below belongs to the named make and communication. Match the complete code, reporting module, model year and engine before applying it.
A code identifies a detected condition, not a part that must automatically be replaced.
Narrow by vehicle
A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Scan worksheet →Manufacturer wording
Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.
C1991MODULE CALIBRATION FAILURE
C1991MODULE CALIBRATION FAILURE
C1991MODULE CALIBRATION FAILURE
Manufacturer communications
4Original wording in English
FORD, MERCURY
DIAGNOSTIC TROUBLE CODE (DTC) C1991 (MODULE CALIBRATION FAILURE) - ANTI-LOCK BRAKE, ADVANCED TRAC, INTERACTIVE VEHICLE DYNAMICS (IVD), TRACTION CONTROL SYSTEM - SERVICE TIP. ALSO INCLUDES FORD FREESTAR MY2005 AND MERCURY MONTEREY MY2005. *TT
FORD, LINCOLN
THIS ARTICLE ADDRESSES THE PROPER PROCEDURE TO CLEAR DIAGNOSTIC TROUBLE CODES C1990 OR C1991 FROM THE VEHICLE DYNAMICS MODULE/4-WHEEL AIR SUSPENSION MODULE. *TT
FORD, LINCOLN
DIAGNOSTICS FOR DIAGNOSTIC TROUBLE CODE C1991 IN THE ABS (ANTILOCK BRAKE SYSTEM) MODULE - OMITTED FROM WORKSHOP MANUAL - PROCEDURE PROVIDED. *TT
FORD, LINCOLN
DIAGNOSTIC PROCEDURES FOR DIAGNOSTIC TROUBLE CODE C1991 (MODULE CALIBRATION FAILURE) OMITTED FROM THE WORSHOP MANUAL. *TT
Check vehicle applicability
4A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
| Make | Model | Model year |
|---|---|---|
| Ford | EXPEDITION ↗ | 2003 |
| Ford | FREESTAR ↗ | 2004 |
| Lincoln | NAVIGATOR ↗ | 2003 |
| Mercury | MONTEREY ↗ | 2004 |
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.