P1A99 Buick Code - Starter/Generator Control Module Hybrid Battery Current Sensor Circuit Low Current
Quick Answer
The purpose of the Accessory Power Module (APM), integral to the Starter/Generator Control Module (SGCM), is to control the amount and direction of energy flowing between the 42 volts DC and 14 volts DC buses via the APM, bi-directional 42 volts DC to 14 volts DC converter. 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
- P1A99 Buick indicates Starter/Generator Control Module Hybrid Battery Current Sensor Circuit Low Current.
- 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.
Code P1A99 Buick Description
The Starter/Generator Control Module (SGCM) controls 2 functions in these DTCs. DC voltage is transformed into three phase AC power to the electric machine interface. In this case, energy flows from 36 volt to phase1, phase2 and phase3. The second case shall be generating, where the three phase AC power is used to charge the 36 volt battery pack. In this case, energy flows from phase1, phase2 and phase3 to 36 volts.
What are the Possible Causes of the DTC P1A99 Buick?
- 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 P1A99 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 is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P1A99 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.
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Frequently Asked Questions about P1A99 Buick Code
1. What does the OBDII code P1A99 mean on a Buick?
P1A99 indicates an issue with the Starter/Generator Control Module detecting a low current reading from the hybrid battery current sensor circuit.
2. What are the common symptoms of code P1A99 on a Buick?
Symptoms may include an illuminated check engine light, reduced fuel efficiency, limited hybrid system functionality, or a decrease in vehicle performance.
3. What causes the P1A99 code on a Buick?
Common causes include a faulty hybrid battery current sensor, damaged wiring or connectors, or an issue with the Starter/Generator Control Module.
4. Can I drive my Buick with the P1A99 code?
While the vehicle may still be drivable, driving with this code could lead to reduced hybrid system performance and possible long-term damage to the hybrid system.
5. How can I diagnose the P1A99 code on my Buick?
Diagnosis typically involves checking the hybrid battery current sensor, inspecting the wiring and connectors, and using a scan tool to monitor sensor readings.
6. How do I fix the P1A99 code on a Buick?
Repairs may include replacing the hybrid battery current sensor, repairing or replacing damaged wiring, or reprogramming or replacing the Starter/Generator Control Module.
7. What tools are needed to troubleshoot code P1A99?
You’ll need an OBDII scan tool, a multimeter to test electrical connections, and potentially a service manual for your specific Buick model.
8. How much does it cost to repair the P1A99 code on a Buick?
Repair costs depend on the specific issue. Replacing a current sensor may cost $200–$400, while module repairs or replacements could be more expensive.
9. Can a weak hybrid battery cause the P1A99 code?
A weak or failing hybrid battery is unlikely to directly cause P1A99, but related issues with the current sensor or control module could trigger the code.
10. Is the P1A99 code specific to Buicks with hybrid systems?
Yes, this code is specific to vehicles with hybrid systems where a Starter/Generator Control Module and hybrid battery current sensors are present.
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