AutoCodes – Generic – P1A79

P1A79 Code - Starter/Generator Control Module Coolant Temperature Sensor 3 Circuit Low Voltage

Quick Answer

The Starter/Generator Control Module (SGCM) monitors its internal fluid temperature sensors to control the SGCM coolant pump and SGCM cooling fan. Common causes include Faulty Starter/Generator Control Module (SGCM), Starter/Generator Control Module (SGCM) harness is open or shorted, Starter/Generator Control Module (SGCM) 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: P1A79 indicates Starter/Generator Control Module Coolant Temperature Sensor 3 Circuit Low Voltage.
Common causes: Common causes include Faulty Starter/Generator Control Module (SGCM), Starter/Generator Control Module (SGCM) harness is open or shorted, Starter/Generator Control Module (SGCM) 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 3,280

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 22, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1A79 Description

The Starter/Generator Control Module (SGCM) monitors its internal fluid temperature sensors to control the SGCM coolant pump and SGCM cooling fan. The internal fluid temperature sensors of the SGCM are thermistors and are not serviceable. When the internal fluid temperatures are cold, the resistances of the sensors are high and the voltage signals are high. When the internal fluid temperatures are hot, the resistances of the sensors are low and the voltage signals are low. The input parameters are not displayed on the scan tool.

OBDII Code P1A79 - Starter/Generator Control Module Coolant Temperature Sensor 3 Circuit Low Voltage - AutoCodes.com — P1A79 Code - Starter/Generator Control Module Coolant Temperature Sensor 3 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P1A79?

Faulty Starter/Generator Control Module (SGCM)
Starter/Generator Control Module (SGCM) harness is open or shorted
Starter/Generator Control Module (SGCM) circuit poor electrical connection

How to Fix the DTC P1A79?

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 P1A79 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

P1A79 Buick — Starter/Generator Control Module Coolant Temperature Sensor 3 Circuit Low Voltage
P1A79 Cadillac — Starter/Generator Control Module Coolant Temperature Sensor 3 Circuit Low Voltage
P1A79 Chevrolet — Starter/Generator Control Module Coolant Temperature Sensor 3 Circuit Low Voltage
P1A79 GMC — Starter/Generator Control Module Coolant Temperature Sensor 3 Circuit Low Voltage
P1A79 Saturn — Starter/Generator Control Module Coolant Temperature Sensor 3 Circuit Low 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 P1A79 Code

1. What are the common symptoms of OBDII code P1A79 (Starter/Generator Control Module Coolant Temperature Sensor 3 Circuit Low Voltage)?

- Common symptoms include poor engine performance, reduced fuel efficiency, and potential starting issues.

2. What typically causes the OBDII code P1A79 to trigger?

- The P1A79 code is often triggered by a malfunction in the Starter/Generator Control Module Coolant Temperature Sensor 3, leading to low voltage readings.

3. How can I diagnose the root cause of OBDII code P1A79?

- A thorough diagnostic process involving checking the sensor wiring, connections, and sensor itself using a multimeter or scan tool is recommended to pinpoint the issue.

4. Can a faulty coolant temperature sensor cause the P1A79 code?

- Yes, a faulty coolant temperature sensor can cause the P1A79 code if it is providing low voltage signals to the control module.

5. What are some repair tips for addressing the P1A79 code?

- Repair tips may include checking and replacing the Starter/Generator Control Module Coolant Temperature Sensor 3, ensuring proper wiring connections, and clearing the code after repairs.

6. How urgent is it to address the OBDII code P1A79?

- While the vehicle may still be operational with the P1A79 code, addressing it promptly is recommended to prevent potential engine performance issues and further damage.

7. Can I drive my vehicle with the P1A79 code present?

- It is generally not recommended to drive the vehicle with the P1A79 code present, as it can lead to poor engine performance and potentially other related problems.

8. Is it possible to clear the P1A79 code without fixing the underlying issue?

- While clearing the code may temporarily turn off the check engine light, it is crucial to address the root cause of the P1A79 code to prevent it from reoccurring.

9. Are there any common related codes that may accompany the P1A79 code?

- Other related codes that may accompany P1A79 include issues with the Starter/Generator Control Module or other coolant temperature sensor circuits.

10. What is the typical cost to repair the OBDII code P1A79?

- The cost to repair the P1A79 code can vary depending on the exact cause of the issue, but it may involve sensor replacement, wiring repairs, or module reprogramming, potentially ranging from $100 to $500 or more.