AutoCodes – Generic – P129B

P129B Code - Absolute Pressure Sensor Intake Pipe Overrun Pressure Implausible

Quick Answer

The Engine Control Module (ECM) monitors the Absolute Pressure Sensor. Common causes include Faulty Absolute Pressure Sensor, Absolute Pressure Sensor harness is open or shorted, Absolute Pressure Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P129B indicates Absolute Pressure Sensor Intake Pipe Overrun Pressure Implausible.
Common causes: Common causes include Faulty Absolute Pressure Sensor, Absolute Pressure Sensor harness is open or shorted, Absolute Pressure Sensor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 12,418

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 08, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P129B Description

The Engine Control Module (ECM) monitors the Absolute Pressure Sensor. The ECM sets the OBDII code when the Absolute Pressure Sensor is not to factory specifications.

OBDII Code P129B - Absolute Pressure Sensor Intake Pipe Overrun Pressure Implausible - AutoCodes.com — P129B Code - Absolute Pressure Sensor Intake Pipe Overrun Pressure Implausible

What does this mean?

What are the Possible Causes of the DTC P129B?

Faulty Absolute Pressure Sensor
Absolute Pressure Sensor harness is open or shorted
Absolute Pressure Sensor circuit poor electrical connection

How to Fix the DTC P129B?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P129B code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P129B code?

Need more information on how to fix the P129B code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P129B code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P129B BMW — Manifold Pressure Sensor Rationality Check
P129B Buick — Fuel Pump Driver Control Module System Voltage Low
P129B Cadillac — Fuel Pump Driver Control Module System Voltage Low
P129B Chevrolet — Fuel Pump Driver Control Module System Voltage Low
P129B GMC — Fuel Pump Driver Control Module System Voltage Low
P129B MINI — Manifold Pressure Sensor Rationality Check

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P129B Code

1. What are the common symptoms of OBDII code P129B?

- Common symptoms include poor engine performance, reduced fuel efficiency, and potential stalling or hesitation during acceleration.

2. What does the OBDII code P129B indicate?

- The code P129B indicates that the absolute pressure sensor in the intake pipe is detecting an implausible pressure reading during overrun conditions.

3. What are the possible causes of OBDII code P129B?

- Possible causes may include a faulty absolute pressure sensor, a vacuum leak in the intake system, a clogged air filter, or issues with the intake manifold.

4. How can I diagnose the OBDII code P129B?

- Diagnosing the code typically involves using a scan tool to read the code, checking the intake system for leaks, inspecting the absolute pressure sensor, and testing the sensor's functionality.

5. Can I continue driving with OBDII code P129B present?

- It is not recommended to continue driving with the code present, as it can lead to further damage to the engine and decrease fuel efficiency.

6. How can I repair OBDII code P129B?

- Repairing the code may involve replacing the absolute pressure sensor, fixing any vacuum leaks, replacing the air filter, or addressing issues with the intake manifold.

7. Is it possible to clear OBDII code P129B without making repairs?

- Clearing the code without addressing the underlying issue is not recommended, as it will likely return once the problem persists.

8. Can a DIY enthusiast fix OBDII code P129B?

- Depending on the root cause, a DIY enthusiast may be able to fix the code by following repair guides and using the necessary tools.

9. How much does it cost to repair OBDII code P129B at a professional mechanic?

- The cost of repair can vary depending on the specific issue, but it may range from $100 to $500 or more, including parts and labor.

10. How often does OBDII code P129B occur in vehicles?

- OBDII code P129B is relatively uncommon compared to other codes, but it can still occur in vehicles with issues related to the absolute pressure sensor and intake system.