P1390 Mercury Code - Octane Adjust Out of Self-Test Range
Quick Answer
The P1390 code for Mercury vehicles indicates that the octane adjust is out of the self-test range. Common causes include Low-quality or incorrect octane fuel, Faulty octane adjust sensor, Wiring or connection issues. 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
- P1390 Mercury indicates Octane Adjust Out of Self-Test Range.
- Common causes
- Common causes include Low-quality or incorrect octane fuel, Faulty octane adjust sensor, Wiring or connection issues.
- 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.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
Code P1390 Mercury Description
The P1390 code for Mercury vehicles indicates that the octane adjust is out of the self-test range. This code is typically associated with the powertrain control module (PCM) detecting that the octane adjust function is operating outside of the predetermined range. The octane adjust function is responsible for adjusting the ignition timing based on the octane level of the fuel being used in the vehicle. When the PCM detects that the octane adjust is not functioning within the specified range, it can negatively impact the vehicle's performance, fuel efficiency, and emissions.
Common Causes of P1390 Mercury
- Low-quality or incorrect octane fuel
- Faulty octane adjust sensor
- Wiring or connection issues
- PCM software glitches
- Engine mechanical issues affecting octane requirements
Symptoms of P1390 Mercury
- Decreased engine performance
- Reduced fuel efficiency
- Engine knocking or pinging
- Illumination of the check engine light
How to Fix P1390 Mercury
- Check the octane level of the fuel being used and ensure it meets the manufacturer's recommended octane rating.
- Inspect the octane adjust sensor for any signs of damage or malfunction. Replace if necessary.
- Check the wiring and connections related to the octane adjust system for any loose or damaged components. Repair or replace as needed.
- Perform a PCM software update or reflash to address any glitches related to the octane adjust function.
- If the issue persists, further diagnostics may be required to identify any underlying engine mechanical issues affecting the octane requirements.
Cost to Fix P1390 Mercury
The typical repair costs for addressing a P1390 code related to the octane adjust out of self-test range can vary depending on the specific cause of the issue. On average, the cost of parts and labor for this repair could range from $100 to $500. However, it's important to note that actual repair costs can vary significantly based on factors such as the location of the repair shop, the vehicle make and model, and the extent of the repairs needed. It's recommended to consult with a qualified mechanic or auto repair shop for a more accurate cost estimate based on the specific circumstances of your vehicle. Labor rates at auto repair shops typically range between $80 and $150 per hour, but rates may differ based on the factors mentioned above.
Need more information about the P1390 Mercury code?
Need more information on how to fix the P1390 Mercury code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P1390 Mercury code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P1390 Mercury Code
No Frequently Asked Questions about P1390 Mercury Code found.
Discuss the causes and fixes for P1390 Mercury OBDII Code
Code P1390 Mercury comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.