P1109 – MAF Sensor In-Range Low Failure (manufacturer-specific)

P1109 Diagnostic Trouble Code: Causes, Symptoms, and Fixes

The P1109 diagnostic trouble code (DTC) indicates a problem with the barometric (BARO) pressure sensor signal being out of the expected range. While this code is not typically an urgent issue that requires immediately stopping driving, it's best to diagnose and repair it promptly to prevent potential drivability problems and ensure optimal engine performance.

Understanding the P1109 Code

The P1109 code is a manufacturer-specific code, meaning its exact definition may vary slightly between automakers. However, it generally points to the engine control module (ECM) detecting a signal voltage from the BARO sensor that is outside the predetermined range.

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.

Vehicles with a P1109 code may experience symptoms like:

• Rough running
• Hesitation on acceleration
• Stalling
• Increased fuel consumption

BARO Sensor Function

The BARO sensor measures atmospheric pressure and provides this data to the ECM. A vehicle's MAP and BARO sensor work together 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.

Common Causes

Several issues can trigger a P1109 code, including:

• Faulty BARO sensor
• Damaged or corroded wiring and connectors
• Vacuum leaks
• Malfunctioning ECM (rare)
• Loose/pushed out pins in the throttle body connector

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.

Diagnosis Steps

To properly diagnose a P1109 code, a mechanic may follow these steps:

1. Scan for other trouble codes. Address any codes that may be related, such as MAP sensor faults.

2. Visually inspect the BARO sensor, wiring, and connections for damage or corrosion. Repair as needed.

3. Test the BARO sensor signal and ground with a digital multimeter. Replace the sensor if readings are out of specification.

4. Check for vacuum leaks at the intake manifold, hoses, and related components. Repair any leaks found.

5. Inspect the throttle body connector pins for any loose or pushed out pins.

6. If no issues are found, the problem may be with the ECM, but this is uncommon. Consult a professional for ECM diagnosis and repair.

Repair Costs

The cost to diagnose and repair a P1109 code can vary depending on the specific issue and labor rates. Expect to pay between $75-$150 for diagnosis. Common repair costs include:

• BARO sensor replacement: $120-$300 (€102-€255)
• Wiring repairs: $50-$200 (€43-€170)
• Vacuum leak repairs: $100-$300 (€85-€255)
• Throttle body replacement: Cost varies

Note that these are general estimates and actual costs may be higher or lower.

Prevention and Related Codes

To help prevent BARO sensor issues, regularly inspect the sensor and wiring for damage and keep the engine well-maintained to avoid vacuum leaks. Codes related to the P1109 include MAP sensor faults like P0105, P0106, and P0107.

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.

By promptly addressing a P1109 code and related issues, you can restore proper engine operation and avoid more serious problems down the road. If you're unsure about diagnosing or repairing this issue, consult a professional mechanic for assistance.

Frequently Asked Questions About P1109

What does the P1109 code mean?

The P1109 code generally indicates an issue with the barometric (BARO) pressure sensor signal being out of the expected range. It’s a manufacturer-specific code that can vary slightly between automakers, but typically points to a problem with the BARO or MAP (Manifold Absolute Pressure) sensor.

Is it safe to drive with a P1109 code?

While not typically an urgent issue requiring immediate stopping, it’s best to diagnose and repair the problem promptly to prevent potential drivability issues and ensure optimal engine performance.

What are the common symptoms of a P1109 code?

Common symptoms include rough running, hesitation on acceleration, stalling, increased fuel consumption, and in some cases, difficulty starting the engine.

What causes a P1109 code?

Common causes include a faulty BARO sensor, damaged wiring or connectors, vacuum leaks, or in rare cases, a malfunctioning Engine Control Module (ECM).

How is a P1109 code diagnosed?

Diagnosis typically involves scanning for other related codes, visually inspecting the BARO sensor and wiring, testing the sensor with a multimeter, and checking for vacuum leaks.

Can I diagnose and fix a P1109 code myself?

While some basic checks can be done at home, proper diagnosis often requires specialized equipment. It’s recommended to have a professional mechanic diagnose and repair the issue.

How much does it cost to fix a P1109 code?

Repair costs can vary depending on the specific issue and labor rates. Diagnosis typically costs between $75-$150. Common repairs range from $120-$300 for sensor replacement to $50-$200 for wiring repairs.

What parts might need to be replaced to fix a P1109 code?

Depending on the specific cause, you might need to replace the BARO sensor, MAP sensor, wiring harness, or in some cases, the throttle body.

Can a P1109 code clear itself?

While codes can sometimes clear themselves if the issue is intermittent, it’s unlikely for a P1109 code to clear without addressing the underlying problem.

How can I prevent a P1109 code from occurring?

Regular maintenance, including inspecting sensors and wiring for damage, and keeping the engine well-maintained to avoid vacuum leaks, can help prevent this issue.

What other codes might appear alongside P1109?

Related codes often include MAP sensor faults like P0105, P0106, and P0107.

Does the P1109 code affect fuel efficiency?

Yes, issues with the BARO or MAP sensor can lead to incorrect fuel mixture calculations, potentially reducing fuel efficiency.

Can a dirty air filter cause a P1109 code?

While unlikely to be the direct cause, a severely clogged air filter could potentially affect sensor readings and contribute to the problem.

How long does it take to fix a P1109 code?

Repair time can vary depending on the specific issue, but typically ranges from 1-3 hours for diagnosis and repair.

Will a P1109 code cause my vehicle to fail an emissions test?

It’s possible, as issues with the BARO or MAP sensor can affect the vehicle’s emissions control system.

Can extreme weather conditions trigger a P1109 code?

While not common, extreme temperature or pressure changes could potentially affect sensor readings and trigger the code.

Is the P1109 code specific to certain vehicle makes or models?

While the code can appear in various vehicles, it’s more common in certain makes like Ford, GM, and some European brands.

Can a faulty oxygen sensor cause a P1109 code?

While not directly related, a faulty oxygen sensor could potentially contribute to incorrect readings and trigger the code.

How does the BARO sensor affect engine performance?

The BARO sensor helps the ECM adjust for changes in atmospheric pressure, which is crucial for optimal fuel mixture and engine performance.

Can I clear the P1109 code without fixing the problem?

While it’s possible to clear the code, it will likely return if the underlying issue isn’t addressed. It’s always best to diagnose and repair the problem rather than simply clearing the code.