P1112 – OBD-II DTC

OBD-II DTC P1112 – Dual Alternator Lower Circuit Malfunction/ Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent Low Voltage

DTC P1112 meaning

DTC P1112 refers to a malfunction in the dual alternator lower circuit or an intermittent low voltage condition in the Manifold Absolute Pressure (MAP) sensor circuit. This code indicates that the vehicle’s onboard diagnostic system has detected an issue with the electrical circuits related to the alternators or the MAP sensor, which can affect engine performance and charging system efficiency.

DTC P1112 symptoms

Common symptoms associated with DTC P1112 may include:

• Illuminated check engine light
• Erratic engine performance
• Difficulty starting the vehicle
• Low battery voltage or charging issues
• Increased fuel consumption

DTC P1112 causes

Several factors can lead to the triggering of DTC P1112, including:

• Faulty MAP sensor
• Wiring issues or damaged connectors in the alternator or MAP sensor circuits
• Defective alternator
• Weak battery or poor battery connections
• Corrosion or poor grounding in the electrical system

DTC P1112 seriousness

DTC P1112 can be considered serious as it may lead to:

• Engine performance issues
• Increased emissions
• Potential damage to the electrical system
• Failure to start the vehicle

Addressing this code promptly is essential to maintain vehicle reliability and performance.

How to diagnose DTC P1112

To diagnose DTC P1112, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the code.
2. Inspect the wiring and connectors related to the MAP sensor and alternators for damage or corrosion.
3. Check the MAP sensor’s voltage and ground connections.
4. Test the alternator output and ensure it is within specifications.
5. Perform a visual inspection of the battery and its connections.
6. Clear the code and perform a road test to see if the code reappears.

How to fix DTC P1112 step-by-step instructions

To fix DTC P1112, follow these steps:

1. Repair or replace any damaged wiring or connectors found during diagnosis.
2. If the MAP sensor is faulty, replace it with a new one.
3. Test and replace the alternator if it is not functioning correctly.
4. Ensure all battery connections are clean and tight.
5. Check and repair any grounding issues in the electrical system.
6. After repairs, clear the DTC and perform a road test to confirm the issue is resolved.

How to erase DTC P1112

To erase DTC P1112, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn the ignition key to the “On” position without starting the engine.
3. Access the scanner’s menu and select the option to clear or erase trouble codes.
4. Confirm the action and wait for the scanner to indicate that the codes have been cleared.
5. Disconnect the scanner and start the vehicle to ensure the check engine light remains off.

Recommended tools for OBD-II diagnostics

Explore our expert picks: The Best OBD2 Scanners for 2025

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.