AutoCodes – Buick – P15A1 Buick

P15A1 Buick Code - Fuel Economy Mode Switch Performance

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: P15A1 Buick indicates Fuel Economy Mode Switch Performance.
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 1,301

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 P15A1 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 P15A1 Buick - Fuel Economy Mode Switch Performance - AutoCodes.com — P15A1 Buick Code - Fuel Economy Mode Switch Performance

What does this mean?

What are the Possible Causes of the DTC P15A1 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 P15A1 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 P15A1 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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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 P15A1 Buick Code

1. What does the OBDII code P15A1 mean on a Buick?

P15A1 indicates an issue with the Fuel Economy Mode Switch Performance, which monitors the operation of the switch controlling fuel-saving modes.

2. What are the common symptoms of code P15A1 in a Buick?

Symptoms may include reduced fuel efficiency, the inability to switch to fuel economy mode, and a potential warning light on the dashboard.

3. What causes the P15A1 code on a Buick?

Common causes include a faulty fuel economy mode switch, wiring issues, or a malfunction in the Body Control Module (BCM).

4. Can I drive my Buick with the P15A1 code?

Yes, but fuel efficiency may be compromised, and ignoring the issue could lead to further electrical problems.

5. How do I diagnose the P15A1 code on my Buick?

Use an OBDII scanner to confirm the code, then inspect the fuel economy mode switch, wiring, and connections for damage or faults.

6. How can I fix the P15A1 code on a Buick?

Repairs may include replacing the fuel economy mode switch, repairing damaged wiring, or reprogramming the BCM as needed.

7. How much does it cost to repair the P15A1 code?

Costs vary depending on the issue but typically range from $100 to $300 for parts and labor.

8. Can a software update resolve the P15A1 code?

In some cases, reprogramming or updating the BCM software can correct the issue, especially if it’s related to system performance glitches.

9. Will disconnecting the battery clear the P15A1 code?

Disconnecting the battery may temporarily clear the code, but the underlying issue must be fixed to prevent it from returning.

10. How can I prevent the P15A1 code from appearing again?

Regular maintenance, inspecting wiring, and ensuring the fuel economy mode switch functions correctly can help prevent recurrence.

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