C1991 Code - Plant Ride Height Setting And/Or Tests Incomplete
Quick Answer
The Air Suspension Control Module monitors the Plant Ride Height Setting. Common causes include Calibrate the ride heights. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- C1991 indicates Plant Ride Height Setting And/Or Tests Incomplete.
- Common causes
- Common causes include Calibrate the ride heights.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code C1991 Description
How to Fix the DTC C1991?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the C1991 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the C1991 code?
Need more information on how to fix the C1991 code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the C1991 code diagnosed by a professional: Find a repair shop in your area
Information for Specific Makes
- C1991 Ford — Plant Ride Height Setting And/Or Tests Incomplete
- C1991 Lincoln — Plant Ride Height Setting And/Or Tests Incomplete
- C1991 Mercury — Plant Ride Height Setting And/Or Tests Incomplete
Frequently Asked Questions about C1991 Code
1. What does the OBDII code C1991 mean?
C1991 indicates that the vehicle's ride height calibration or testing procedure is incomplete or has failed during the self-diagnosis process.
2. What are the common symptoms of code C1991?
Symptoms may include improper vehicle ride height, uneven suspension, suspension warning lights on the dashboard, or poor handling.
3. What causes the C1991 code to appear?
Common causes include incomplete or interrupted ride height calibration, faulty ride height sensors, damaged wiring, or issues with the suspension control module.
4. Can a faulty ride height sensor trigger the C1991 code?
Yes, a malfunctioning ride height sensor can prevent proper calibration and cause the C1991 code to set.
5. How do I fix the C1991 code?
Check the ride height sensors and wiring for damage, ensure the calibration process is completed using a scan tool, and replace any faulty components if needed.
6. Do I need special tools to address the C1991 code?
Yes, resolving C1991 typically requires a scan tool capable of performing ride height calibration and accessing suspension system diagnostics.
7. Can I drive with the C1991 code active?
Driving is possible but not recommended, as improper ride height can affect handling, stability, and wear on suspension components.
8. How do I perform the ride height calibration for C1991?
Refer to the manufacturer’s service manual for step-by-step instructions, as calibration often requires a scan tool and specific environmental conditions.
9. Could a dead battery cause the C1991 code?
Yes, a dead or disconnected battery can reset the system and interrupt the ride height calibration, potentially triggering the code.
10. Will clearing the C1991 code with a scan tool fix the issue?
Clearing the code may temporarily turn off the warning, but the underlying issue must be resolved to prevent the code from returning.
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