The P1109 code is a manufacturer-specific fault code. It means that the engine control module (ECM) has detected a signal voltage from the barometric (BARO) pressure sensor that is out of the predetermined range.
Because this is a manufacturer-specific code, each automaker may have a slightly different definition, steps for diagnosis, and repair information. Automakers with a P1109 trouble code include, but are not limited to Audi, Citroen/Peugeot, Daewoo, Fiat, Ford, General Motors, Lincoln, Mercury, Mini, Oldsmobile, Volkswagen, and Volvo.
Codes related to the P1109 include:
- P0068: MAP/MAF – Throttle Position Correlation
- P0105: Manifold Absolute Pressure/Barometric Pressure Circuit
- P0106: Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
- P0107: Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
- P0108: Manifold Absolute Pressure/Barometric Pressure Circuit High Input
- P0109: Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent
- P0316: Engine Misfire Detected on Startup (First 1000 Revolutions)
- P2073: Manifold Absolute Pressure/Mass Air Flow - Throttle Position Correlation at Idle
- P2074: Manifold Absolute Pressure/Mass Air Flow - Throttle Position Correlation at Higher Load
- P2226: Barometric Pressure Circuit
- P2227: Barometric Pressure Circuit Range/Performance
- P2228: Barometric Pressure Circuit Low
- P2229: Barometric Pressure Circuit High
- P2230: Barometric Pressure Circuit Intermittent
What the P1109 code means
For most automakers, a code P1109 will be stored when the wrong manifold air pressure (MAP) sensor voltage reading is detected for a preset amount of time, typically four seconds.
A vehicle’s MAP and BARO sensor work to provide the ECM with information related to the amount or degree of air pressure, or vacuum, that is in the intake manifold at a given point in time. The ECM will then use the data to help calculate the best fuel delivery strategy for the most efficient engine operation.
What causes the P1109 code?
Several problems may cause a P1109 code including:
- Damaged or defective electrical wiring
- Damaged or defective BARO pressure sensor
- Damaged or defective MAP sensor
- Damaged or defective mass airflow (MAF) sensor
- Damaged or defective throttle position sensor
- Clogged catalytic converter
- Incorrect software installed in ECM
- Damaged or defective ECM
What are the symptoms of the P1109 code?
Symptoms of a P1109 code may include:
- Check engine or warning light may illuminate
- Vehicle may idle roughly
- Engine may hesitate during acceleration
- Decreased fuel economy
How does a mechanic diagnose the P1109 code?
A mechanic may use several methods to diagnose a P1109 trouble code, including:
- Utilize an OBD-II scanner to check for a stored P1109 trouble code
- Visually inspect wiring and related electrical components for damage or corrosion
- Check for problems with the mass airflow (MAF) sensor or trouble codes and diagnose
- Check for any additional MAP trouble codes and diagnose
- Check for engine misfire codes and diagnose
- Check for issue with the mass air flow (MAF) circuit
- Check for unmetered air entering the engine
- Check for insufficient air supply to the engine
- Check for a clogged filter
- Check for a damaged or defective air inlet pipe
- Check for clogged catalytic converter(s)
- Check for any vacuum leaks
- Check power and ground at MAP and BARO sensors
- Test sensors using automaker recommendations
- Check for damaged or dirty hot wire to MAF
Common mistakes when diagnosing the P1109 code
It is possible to misdiagnose the cause of a P1109 code to be either the MAP or BARO sensor, when the true problem is related to electrical wiring and circuitry.
How serious is the P1109 code?
Because a vehicle’s safe driving operation most likely will not be impacted due to faults that store a P1109 code, this code is not considered a potentially serious code. When this code appears, it is recommended to take your vehicle to your local service center or mechanic for repair and diagnosis as soon as you can.
What repairs can fix the P1109 code?
Several repairs can fix a P1109 trouble code and include:
- Replace damaged or corroded, loose, or shorted electrical wiring and related connectors
- Repair any mass airflow, manifold air pressure, and engine misfire codes that were also stored
- Repair any damage or problems with the MAF circuitry
- Repair or replace clogged or damaged filters
- Repair damaged or defective air inlet pipe
- Clear clogged catalytic converter(s)
- Repair vacuum leaks
- Replace damaged or defective MAP sensor
- Replace damaged or defective BARO sensor
- Clean hot wire to MAF
- Replace damaged or defective ECM and reprogram
- Clear all codes, test-drive the vehicle, and rescan to see if any codes reappear
Need help with a P1109 code?
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