AutoCodes – Generic – P18C5

P18C5 Code - Gear Position Sensor Circuit 1 High Voltage

Quick Answer

The gear position sensor is a switching transistor mounted to the top of the transmission extension housing. Common causes include Faulty Gear Position Sensor, Gear Position Sensor harness is open or shorted, Gear Position 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: P18C5 indicates Gear Position Sensor Circuit 1 High Voltage.
Common causes: Common causes include Faulty Gear Position Sensor, Gear Position Sensor harness is open or shorted, Gear Position 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 2,407

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 Feb 05, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P18C5 Description

The gear position sensor is a switching transistor mounted to the top of the transmission extension housing. The four wire sensor interfaces directly with the Engine Control Module (ECM). The ECM supplies 5 V to the gear position sensor on a 5 V reference circuit and also provides a ground path on a low reference circuit. The sensor provides a Pulse Width Modulated (PWM) duty cycle to the ECM on two signal circuits that is proportional to the linear and radial position of the corresponding magnet assembly mounted to the shift shaft. The vehicle uses the gear position sensor information primarily for Active Rev Matching and Active Fuel Management. The ECM monitors the radial position signal 1 circuit for low and high voltage conditions.

OBDII Code P18C5 - Gear Position Sensor Circuit 1 High Voltage - AutoCodes.com — P18C5 Code - Gear Position Sensor Circuit 1 High Voltage

What does this mean?

What are the Possible Causes of the DTC P18C5?

Faulty Gear Position Sensor
Gear Position Sensor harness is open or shorted
Gear Position Sensor circuit poor electrical connection

How to Fix the DTC P18C5?

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 P18C5 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.

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Information for Specific Makes

P18C5 Buick — Gear Position Sensor Circuit 1 High Voltage
P18C5 Cadillac — Gear Position Sensor Circuit 1 High Voltage
P18C5 Chevrolet — Gear Position Sensor Circuit 1 High Voltage
P18C5 GMC — Gear Position Sensor Circuit 1 High Voltage

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 P18C5 Code

1. What are the common symptoms of OBDII code P18C5 (Gear Position Sensor Circuit 1 High Voltage)?

- Common symptoms include issues with gear shifting, hesitation or jerking during acceleration, and the transmission not responding properly.

2. What are the possible causes of OBDII code P18C5?

- The code P18C5 can be triggered by a faulty gear position sensor, damaged wiring or connectors in the sensor circuit, or software issues in the transmission control module.

3. How can I diagnose the cause of OBDII code P18C5?

- Diagnosis involves checking the gear position sensor for proper operation, inspecting the sensor circuit for any damage, and scanning the transmission control module for related error codes.

4. Can I continue driving with OBDII code P18C5 present?

- It is not recommended to drive with the P18C5 code active, as it can lead to further transmission problems and potentially unsafe driving conditions.

5. How can I repair OBDII code P18C5?

- Repairing the P18C5 code typically involves replacing the faulty gear position sensor, repairing any damaged wiring or connectors, and resetting the transmission control module.

6. Is it possible to reset the OBDII code P18C5 without making any repairs?

- While clearing the code may temporarily turn off the check engine light, the underlying issue causing the P18C5 code will persist until properly addressed.

7. Are there any DIY tips for fixing OBDII code P18C5?

- DIY enthusiasts can attempt to check the gear position sensor and its connections for visible damage, but for accurate diagnosis and repair, it is recommended to consult a professional mechanic.

8. What can happen if OBDII code P18C5 is left untreated?

- Ignoring the P18C5 code can lead to continued transmission issues, potential damage to the transmission system, and increased risk of complete transmission failure.

9. How long does it typically take to repair OBDII code P18C5?

- The repair time for the P18C5 code can vary depending on the exact cause of the issue, but it generally takes a few hours to a day for a skilled mechanic to diagnose and fix the problem.

10. Can the OBDII code P18C5 be intermittent?

- Yes, the P18C5 code can sometimes be intermittent, especially if the issue is related to loose wiring or intermittent sensor malfunctions.