AutoCodes – Buick – P15A0 Buick

P15A0 Buick Code - Fuel Economy Mode Switch Circuit High Voltage

Quick Answer

The Engine Control Module (ECM) supplies 5 V reference voltage, through the 5 V reference voltage circuit, to the S87 fuel economy mode switch. Common causes include Faulty Fuel Economy Mode Switch, Fuel Economy Mode Switch harness is open or shorted, Fuel Economy Mode Switch 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: P15A0 Buick indicates Fuel Economy Mode Switch Circuit High Voltage.
Common causes: Common causes include Faulty Fuel Economy Mode Switch, Fuel Economy Mode Switch harness is open or shorted, Fuel Economy Mode Switch 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 1,714

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 Jan 02, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P15A0 Buick Description

The Engine Control Module (ECM) supplies 5 V reference voltage, through the 5 V reference voltage circuit, to the S87 fuel economy mode switch. The 5 V reference voltage causes current to flow through a series of resistors in the switch to the switch ground circuit. The ECM monitors the reference voltage through a discrete fuel economy mode switch signal circuit. When the switch button is momentarily pressed, the switch contacts allow the 5 V reference voltage to by-pass one of the resistors. The ECM detects the resulting voltage drop as a fuel economy mode request and sends a GMLAN message to the Transmission Control Module (TCM) indicating the request. When the TCM receives the request, throttle progressions and transmission shift points are modified to optimize fuel efficiency. The Instrument Panel Cluster (IPC) also receives the fuel economy mode request message from the ECM and illuminates the fuel economy mode indicator lamp. The fuel economy mode switch must be pressed for between 0.094-1.5 s to activate the fuel economy mode.

OBDII Code P15A0 Buick - Fuel Economy Mode Switch Circuit High Voltage - AutoCodes.com — P15A0 Buick Code - Fuel Economy Mode Switch Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P15A0 Buick?

Faulty Fuel Economy Mode Switch
Fuel Economy Mode Switch harness is open or shorted
Fuel Economy Mode Switch circuit poor electrical connection

How to Fix the DTC P15A0 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 P15A0 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 P15A0 Buick code?

Need more information on how to fix the P15A0 Buick code? Get Access to Factory Service Manuals

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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 P15A0 Buick Code

1. What does the OBDII code P15A0 mean on a Buick?

P15A0 indicates a "Fuel Economy Mode Switch Circuit High Voltage," meaning the vehicle's control module has detected an abnormally high voltage in the fuel economy mode switch circuit.

2. What are the common symptoms of the P15A0 code on a Buick?

Symptoms may include the fuel economy mode switch not functioning, failure to activate or deactivate fuel-saving modes, and possibly an illuminated check engine light.

3. What causes the P15A0 code to appear?

Common causes include a faulty fuel economy mode switch, damaged wiring or connectors in the circuit, or a malfunctioning body control module (BCM).

4. How can I diagnose the P15A0 code on my Buick?

Start by checking the wiring and connectors for damage, corrosion, or loose connections. Then, test the fuel economy mode switch for proper operation and inspect the circuit voltage with a multimeter.

5. Can I still drive my Buick with the P15A0 code active?

Yes, you can still drive the vehicle, but the fuel economy mode may not function properly, potentially impacting fuel efficiency.

6. How do I fix the P15A0 code on a Buick?

Repairs may involve replacing a faulty fuel economy mode switch, repairing damaged wiring or connectors, or reprogramming or replacing the body control module if necessary.

7. How much does it cost to fix the P15A0 code on a Buick?

Repair costs can vary, but replacing a fuel economy mode switch may cost $100-$300, while wiring repairs or BCM replacement could cost more depending on labor and parts.

8. Can a weak battery cause the P15A0 code to appear?

A weak or failing battery typically wouldnâ€™t cause this specific code, but electrical system issues can sometimes contribute to circuit-related errors.

9. Will clearing the P15A0 code solve the problem?

Clearing the code may temporarily turn off the check engine light, but the underlying issue must be fixed to prevent the code from returning.

10. Can the P15A0 code cause other problems if left unresolved?

While it typically wonâ€™t cause severe damage, ignoring the P15A0 code may lead to reduced fuel efficiency or additional electrical issues over time.