AutoCodes – Generic – P04A9

P04A9 Code - Exhaust Pressure Control Valve 'B' Position Sensor/Switch Circuit High

Quick Answer

The Powertrain Control Module (PCM) monitors the Exhaust Pressure Control Valve Position Sensor. Common causes include Faulty Exhaust Pressure Control Valve 'B' Position Sensor/Switch, Exhaust Pressure Control Valve 'B' Position Sensor/Switch harness is open or shorted, Exhaust Pressure Control Valve 'B' Position Sensor/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: P04A9 indicates Exhaust Pressure Control Valve 'B' Position Sensor/Switch Circuit High.
Common causes: Common causes include Faulty Exhaust Pressure Control Valve 'B' Position Sensor/Switch, Exhaust Pressure Control Valve 'B' Position Sensor/Switch harness is open or shorted, Exhaust Pressure Control Valve 'B' Position Sensor/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 1,841

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 Apr 26, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
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Code P04A9 Description

The Powertrain Control Module (PCM) monitors the Exhaust Pressure Control Valve Position Sensor. The PCM sets the OBDII code when the Exhaust Pressure Control Valve Position Sensor is not to factory specifications.

OBDII Code P04A9 - Exhaust Pressure Control Valve 'B' Position Sensor/Switch Circuit High - AutoCodes.com — P04A9 Code - Exhaust Pressure Control Valve 'B' Position Sensor/Switch Circuit High

What does this mean?

What are the Possible Causes of the DTC P04A9?

Faulty Exhaust Pressure Control Valve 'B' Position Sensor/Switch
Exhaust Pressure Control Valve 'B' Position Sensor/Switch harness is open or shorted
Exhaust Pressure Control Valve 'B' Position Sensor/Switch circuit poor electrical connection

How to Fix the DTC P04A9?

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 P04A9 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.