AutoCodes – Buick – C0305 Buick

C0305 Buick Code - Front Propshaft Speed Sensor

Quick Answer

The Front Propshaft Speed Sensor is a permanent magnet (PM) generator. Common causes include Faulty Front Propshaft Speed Sensor, Front Propshaft Speed Sensor harness is open or shorted, Front Propshaft Speed 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: C0305 Buick indicates Front Propshaft Speed Sensor.
Common causes: Common causes include Faulty Front Propshaft Speed Sensor, Front Propshaft Speed Sensor harness is open or shorted, Front Propshaft Speed 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 845

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 Jun 18, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code C0305 Buick Description

The Front Propshaft Speed Sensor is a permanent magnet (PM) generator. The PM generator produces a pulsing AC voltage. The AC voltage level and number of pulses increases as speed increases. The transfer case shift control module converts the pulsating AC voltage to a propshaft RPM which is used for the following functions:
- Calculations
- To monitor the difference between the front and rear propshaft speed
- In the AUTO, or the Adapt mode of operation, to determine the amount of slip and the percent of torque to apply to the front axle
The module accesses this input when the vehicle is in AUTO mode, 4HI, and 4LO ranges. The propshaft RPM can be displayed with a scan tool.

This DTC detects an open, short to ground, short to voltage or faulty sensor.

OBDII Code C0305 Buick - Front Propshaft Speed Sensor - AutoCodes.com — C0305 Buick Code - Front Propshaft Speed Sensor

What does this mean?

What are the Possible Causes of the DTC C0305 Buick?

Faulty Front Propshaft Speed Sensor
Front Propshaft Speed Sensor harness is open or shorted
Front Propshaft Speed Sensor circuit poor electrical connection

How to Fix the DTC C0305 Buick?

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 does this mean?

Code Tech Notes

There is factory service bulletin for the C0305 code. The factory recommends reprogramming the Transfer Case Control Module (TCCOM) to fix the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C0305 Buick 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 C0305 Buick code?

Need more information on how to fix the C0305 Buick code? Get Access to Factory Service Manuals

Need Help with the Code?

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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 C0305 Buick Code

1. What does OBDII code C0305 mean on a Buick?

Code C0305 indicates an issue with the Front Propshaft Speed Sensor circuit, which monitors the rotational speed of the front propshaft in the drivetrain.

2. What are the symptoms of code C0305 on a Buick?

Common symptoms include the service 4WD or AWD warning light, reduced traction system performance, and possible issues with engaging the 4WD or AWD system.

3. What causes the C0305 code to appear?

Possible causes include a faulty front propshaft speed sensor, damaged wiring or connectors in the sensor circuit, or a malfunctioning transfer case control module (TCCM).

4. How do you diagnose a C0305 code on a Buick?

Diagnosis involves checking the sensor wiring and connectors for damage, testing the resistance of the front propshaft speed sensor, and using a scan tool to monitor sensor data.

5. Can you drive with a C0305 code on a Buick?

While the vehicle may still be drivable, the AWD or 4WD system may not function properly, which can affect traction and stability in certain driving conditions.

6. How do you fix code C0305 on a Buick?

Repairs may involve replacing the front propshaft speed sensor, repairing damaged wiring or connectors, or reprogramming/replacing the transfer case control module if necessary.

7. How much does it cost to fix code C0305 on a Buick?

The cost can vary, but replacing the front propshaft speed sensor typically ranges from $100 to $300, including parts and labor.

8. Can a bad front propshaft speed sensor damage other components?

If left unresolved, a faulty sensor can lead to improper operation of the AWD/4WD system, potentially causing additional wear on drivetrain components.

9. How can you prevent code C0305 from recurring?

Regular maintenance, including inspecting and securing wiring and connectors, can help prevent issues with the front propshaft speed sensor.

10. Is a professional mechanic required to fix a C0305 code?

While experienced DIYers with the right tools can attempt repairs, diagnosing and fixing this code is often best left to a qualified mechanic to ensure proper function of the AWD/4WD system.