P1106
SubaruDual Alternator Lower Fault/ Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent High Voltage
Medium SeverityThe P1106 code for Subaru vehicles indicates an intermittent high voltage signal from the Manifold Absolute Pressure (MAP) Sensor circuit or a fault with the dual alternator system. This can lead to the engine's computer receiving incorrect air intake readings, affecting engine performance and fuel economy.
⚠️ Before You Begin (Safety First)
Always ensure the vehicle is safely parked and turned off before performing any inspections or repairs. Disconnect the battery's negative terminal to prevent electrical shock or damage to the vehicle's electrical system.
Common Symptoms
- Check Engine Light illumination
- Rough idle or stalling
- Poor engine acceleration
- Reduced fuel economy
- Black smoke from the exhaust
- Engine running rich (too much fuel)
Common Causes
- Faulty Manifold Absolute Pressure (MAP) sensor
- Damaged or corroded wiring or connectors in the MAP sensor circuit
- Vacuum leaks affecting MAP sensor readings
- Issues with the Engine Control Unit (ECU)
- Problems with the dual alternator system (less common for MAP sensor related symptoms)
Frequently reported on: Subaru Impreza 2008-2014, Subaru Forester 2009-2013, Subaru Legacy 2005-2009, Subaru Outback 2005-2009
Diagnostic Steps
- Locate the MAP sensor, typically on the intake manifold.
- Inspect the MAP sensor's electrical connector and wiring for any signs of damage, corrosion, or loose connections. Repair as necessary.
- Check for any obvious vacuum leaks around the intake manifold or vacuum lines connected to the MAP sensor.
- Carefully remove the MAP sensor and inspect its port for carbon buildup or debris. Clean if necessary with a specific MAF/MAP sensor cleaner.
- If possible, test the MAP sensor's voltage output with a multimeter according to your vehicle's service manual specifications.
- If the sensor is deemed faulty or if visual inspection and cleaning do not resolve the issue, replace the MAP sensor with a new, quality part.
- Clear the P1106 code using an OBD-II scanner and test drive the vehicle to see if the code returns.
👨🔧 When to Call a Professional
If you have performed basic troubleshooting and the code persists, or if you are unsure about testing electrical circuits, it is best to consult a qualified automotive technician. Intermittent electrical issues can be challenging to diagnose without specialized tools.
Commonly Asked Questions
What does 'intermittent high voltage' mean for my MAP sensor?
It means the sensor is occasionally sending a voltage signal that is too high to the engine's computer, suggesting it's seeing more pressure (or less vacuum) than it should. This erratic signal can confuse the ECU and cause performance issues.
Can a dirty MAP sensor cause a P1106 code?
Yes, a dirty or clogged MAP sensor port can give inaccurate readings, potentially leading to intermittent high voltage signals. Cleaning it is a good first step in troubleshooting.
Is it safe to drive with a P1106 code?
While the car might still run, driving with a P1106 code can lead to poor fuel economy, reduced engine performance, and potentially damage other engine components due to an incorrect air/fuel mixture. It's best to address it promptly.
How do I confirm if my MAP sensor is faulty?
The most reliable way is to test its voltage output with a multimeter while it's connected and the engine is running (or key on, engine off) and compare readings to your vehicle's service manual specifications. An OBD-II scanner can also show live MAP sensor data.
Could a vacuum leak trigger the P1106 code?
Yes, a significant vacuum leak can cause the MAP sensor to read incorrect manifold pressure, which might lead to the ECU interpreting the signal as an intermittent high voltage, even if the sensor itself is fine.