P112E – Manifold Absolute Pressure at Accelerator Angle Too Low, Bank 1

Code P112E: Malfunction of the MAP Sensor or Circuit

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Probable Causes:

• Faulty MAP sensor (internal failure or abnormal response).

• Electrical problem: Damaged sensor wiring (open circuit, short circuit), oxidized connectors, or broken pins.

• Faulty connection: Poor sensor mounting or corrosion at the terminals.

• Electronic throttle actuator failure (related to synchronization with the MAP sensor).

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Symptoms:

• Check engine light on (or “Service engine soon” message).

• Unstable idle or engine stalling.

• Loss of power or hesitation during acceleration.

• Increased fuel consumption.

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Meaning of Code P112E:
The MAP (Manifold Absolute Pressure) sensor measures the vacuum in the intake manifold to determine engine load. This data is used by the ECU to adjust:

• Fuel injection.

• Ignition timing.

• Idle speed control.

Code P112E is triggered when the ECU detects an inconsistency between:

• The throttle pedal position (via the electronic actuator).

• The vacuum measured by the MAP sensor.
  For example, a MAP signal that is too low at full throttle (where vacuum should be nearly zero) indicates a fault.

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Diagnostic Procedure:

1. Visual inspection:

   • Check the MAP sensor, its connector, and the wiring harness (look for cut wires, corrosion, or physical damage).

   • Check the intake system for leaks (vacuum leaks distort readings).

2. Electrical test:

   • Measure the sensor supply voltage (typically 5V) and ground with a multimeter.

   • Check the MAP output signal (varies with vacuum: ~1V at full throttle, ~4-5V at idle).

3. Data analysis:

   • Use an OBD-II scanner to observe real-time MAP sensor values. Compare them to expected values (e.g., 30-50 kPa at idle, ~100 kPa at full throttle).

4. Throttle actuator check:

   • Test its resistance and operation via the ECU (some scanners allow manual actuator activation).

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Repair Procedure:

1. MAP sensor replacement:

   • Disconnect the battery before any work.

   • Install a new sensor that meets manufacturer specifications (avoid low-quality parts).

2. Electrical circuit repair:

   • Repair or replace damaged wires. Clean connectors with contact cleaner.

3. Code reset:

   • Clear the P112E code with an OBD-II scanner after repairs. Perform a drive cycle to confirm the issue is resolved.

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Technical Tips:

• Check for vacuum leaks: A cracked intake manifold or detached hose disrupts MAP readings. Use a smoke machine or leak detection spray.

• Software update: On some vehicles, an ECU recalibration using manufacturer software is required.

• Prioritize comprehensive diagnostics: A faulty throttle actuator may be a secondary symptom (e.g., issue with EGR valve or turbocharger).