AutoCodes – Generic – P1A9E

P1A9E Code - Starter/Generator Inverter Phase U Overtemperature

Quick Answer

The Power Inverter Module (PIM) temperature 1 and 2 sensors are used for overheat protection. 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: P1A9E indicates Starter/Generator Inverter Phase U Overtemperature.
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 1,287

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 24, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1A9E Description

The Power Inverter Module (PIM) temperature 1 and 2 sensors are used for overheat protection. The thermistors are located on the control board, near the phase U or V power MOSFET. The Starter/Generator Control Module (SGCM) monitors the inverter temperature sensor for the following:
To detect if the inverter phase U or V temperature sensor is shorted low.
To detect if the inverter phase U or V temperature sensor is shorted high.

OBDII Code P1A9E - Starter/Generator Inverter Phase U Overtemperature - AutoCodes.com — P1A9E Code - Starter/Generator Inverter Phase U Overtemperature

What does this mean?

What are the Possible Causes of the DTC P1A9E?

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 P1A9E?

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 P1A9E 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 P1A9E code?

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Information for Specific Makes

P1A9E Buick — Starter/Generator Inverter Phase U Overtemperature
P1A9E Cadillac — Starter/Generator Inverter Phase U Overtemperature
P1A9E Chevrolet — Starter/Generator Inverter Phase U Overtemperature
P1A9E GMC — Starter/Generator Inverter Phase U Overtemperature
P1A9E Saturn — Starter/Generator Inverter Phase U Overtemperature

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 P1A9E Code

1. What does the OBDII code P1A9E mean?

The P1A9E code indicates that the starter/generator inverter's Phase U circuit has detected an overtemperature condition, signaling a potential thermal issue.

2. What are the common symptoms of the P1A9E code?

Symptoms may include the hybrid system warning light, reduced vehicle performance, limited charging capability, or the engine failing to start in hybrid vehicles.

3. What causes the P1A9E code to appear?

The most common causes include overheating of the starter/generator inverter due to a malfunctioning cooling system, electrical faults, or excessive load on the inverter.

4. Can driving with the P1A9E code cause further damage?

Yes, driving with this code can lead to permanent damage to the inverter or other hybrid system components due to prolonged overheating.

5. How is the P1A9E code diagnosed?

A technician will use a scan tool to confirm the code, inspect the inverter cooling system, check for electrical faults in the Phase U circuit, and ensure proper operation of the inverter.

6. What repairs are typically needed for the P1A9E code?

Repairs may include flushing or repairing the cooling system, replacing the inverter, fixing wiring or connector issues, or addressing any excessive load conditions.

7. Can low coolant cause the P1A9E code?

Yes, low or contaminated coolant in the inverter's cooling system can lead to overheating and trigger this code.

8. How much does it cost to fix the P1A9E code?

Costs can vary widely depending on the cause, ranging from $100 for minor cooling system repairs to over $2,000 for inverter replacement.

9. Is the P1A9E code specific to hybrid or electric vehicles?

Yes, this code is specific to hybrid or electric vehicles equipped with a starter/generator inverter system.

10. What preventative maintenance can help avoid the P1A9E code?

Regularly checking and maintaining the inverter's cooling system, inspecting electrical connections, and avoiding excessive strain on the hybrid system can help prevent this issue.