AutoCodes – Mercury – P2259 Mercury

P2259 Mercury Code - Secondary Air Injection System Control 'B' Circuit Low

Quick Answer

An Air Pump is used on the vehicle to lower tail pipe emissions on start-up. Common causes include Faulty Secondary Air System Relay, Secondary Air System Relay harness is open or shorted, Secondary Air System Relay 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: P2259 Mercury indicates Secondary Air Injection System Control 'B' Circuit Low.
Common causes: Common causes include Faulty Secondary Air System Relay, Secondary Air System Relay harness is open or shorted, Secondary Air System Relay 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 1,298

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 Jun 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P2259 Mercury Description

An Air Pump is used on the vehicle to lower tail pipe emissions on start-up. The Powertrain Control Module (PCM) grounds the Air Pump Relay Control Circuit which energizes the Air Pump. The PCM also grounds the Air Combination Valve Vacuum Control Solenoid Circuit, which energizes the Air Vacuum Control Solenoid. Vacuum is then applied to both Air Combination Valve Diaphragms which opens the shut-off valves. The PCM enables both circuits simultaneously when Air System operation is desired. When the Air System is active, then Air pump forces fresh air into the exhaust stream in order to accelerate catalyst operation. The AIR combination valves replace the conventional check valves. When the AIR system is inactive the shut-off valves prevent air flow in either direction.

OBDII Code P2259 Mercury - Secondary Air Injection System Control 'B' Circuit Low - AutoCodes.com — P2259 Mercury Code - Secondary Air Injection System Control 'B' Circuit Low

What does this mean?

What are the Possible Causes of the DTC P2259 Mercury?

Faulty Secondary Air System Relay
Secondary Air System Relay harness is open or shorted
Secondary Air System Relay circuit poor electrical connection
Faulty Secondary Air System Pump

How to Fix the DTC P2259 Mercury?

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 P2259 Mercury 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.