Understanding OBD DTC GM P1105: Meaning and Troubleshooting Guide

Understanding OBD DTC GM P1105: Meaning and Troubleshooting Guide

The Diagnostic Trouble Code (DTC) P1105 for General Motors (GM) vehicles typically refers to a problem with the Manifold Absolute Pressure (MAP) sensor or the Barometric Pressure (BARO) sensor. Specifically, it indicates a malfunction in the MAP/BARO switch solenoid valve, which is responsible for monitoring and regulating the pressure in the intake manifold and the atmospheric pressure.

How Serious Is This Issue?

The severity of the P1105 code can vary. While it may not immediately cause severe damage to your vehicle, it can lead to performance issues and reduced fuel efficiency. Ignoring this issue for an extended period can result in more significant problems, such as engine misfires or damage to other components.

Is It Safe to Drive with This DTC Code?

Driving with a P1105 code is generally not recommended. The malfunctioning MAP/BARO sensor can cause the engine to run inefficiently, leading to poor performance and potential safety risks. It’s best to address the issue as soon as possible to avoid further complications.

Symptoms and Common Causes


  • Check Engine Light (CEL) illuminated
  • Poor engine performance
  • Reduced fuel efficiency
  • Engine stalling or rough idling
  • Black exhaust smoke

Common Causes:

  • Faulty MAP/BARO switch solenoid
  • Damaged or disconnected vacuum hoses
  • Electrical issues such as damaged wiring or connectors
  • Faulty MAP sensor
  • Issues with the vehicle’s Powertrain Control Module (PCM)

How Can I Fix It?

To fix the P1105 code, follow these steps:

  1. Inspect Vacuum Hoses: Check for any cracks, disconnections, or damage in the vacuum hoses connected to the MAP/BARO switch solenoid.
  2. Test the Solenoid: Use a multimeter to test the solenoid for proper voltage and functionality.
  3. Check Electrical Connections: Inspect the wiring and connectors for any signs of damage or corrosion.
  4. Replace Faulty Components: If the MAP/BARO switch solenoid or MAP sensor is faulty, replace them.
  5. Reset the Code: After making the necessary repairs, use an OBD-II scanner to clear the code and reset the Check Engine Light.

Can I Fix This DTC Code Myself?

Yes, if you have basic mechanical skills and the right tools, you can fix the P1105 code yourself. You’ll need a multimeter, vacuum pump, and possibly some replacement parts like vacuum hoses or sensors. However, if you’re not comfortable with diagnosing and repairing vehicle issues, it’s best to consult a professional mechanic.

Parts That Might Need Replacement and Repair Costs


  • MAP/BARO switch solenoid
  • MAP sensor
  • Vacuum hoses
  • Electrical connectors or wiring


  • MAP/BARO switch solenoid: $50 – $150
  • MAP sensor: $30 – $100
  • Vacuum hoses: $10 – $30
  • Labor costs: $50 – $150 per hour (if you hire a mechanic)

Will the Repair Be Expensive?

The cost of repairing a P1105 code can vary depending on the specific issue and the parts that need replacement. Generally, it is not considered a very expensive repair, especially if you can perform the work yourself. However, labor costs can add up if you need professional assistance.

Can I Reset the DTC Code Myself?

Yes, you can reset the DTC code yourself using an OBD-II scanner. After performing the necessary repairs, connect the scanner to your vehicle’s OBD-II port, follow the instructions to clear the code, and reset the Check Engine Light.

Will It Affect Performance or Fuel Efficiency?

Yes, a P1105 code can significantly affect your vehicle’s performance and fuel efficiency. The MAP/BARO sensor plays a crucial role in the engine’s air-fuel mixture regulation. A malfunction can lead to poor engine performance, increased fuel consumption, and potential stalling issues.

How Can I Prevent It in the Future?

To prevent the P1105 code from recurring:

  • Regularly inspect and maintain vacuum hoses and electrical connections.
  • Ensure the MAP/BARO switch solenoid and MAP sensor are in good working condition.
  • Perform routine vehicle maintenance and address any issues promptly.
  • Use high-quality replacement parts to avoid premature failures.

By following these guidelines, you can ensure your vehicle runs smoothly and efficiently, minimizing the chances of encountering the P1105 code again.

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