AutoCodes – Cadillac – P1646 Cadillac

P1646 Cadillac Code - EVAP Vent Solenoid Output Circuit

Quick Answer

The Powertrain Control Module (PCM) contains chips called Output Driver Modules that provide 7 switchable ground outputs for operating solenoids, relays, telltales, and other devices. Common causes include Faulty EVAP Vent Solenoid, EVAP Vent Solenoid harness is open or shorted, EVAP Vent Solenoid 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: P1646 Cadillac indicates EVAP Vent Solenoid Output Circuit.
Common causes: Common causes include Faulty EVAP Vent Solenoid, EVAP Vent Solenoid harness is open or shorted, EVAP Vent Solenoid 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 9,662

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 Sep 05, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1646 Cadillac Description

The Powertrain Control Module (PCM) contains chips called Output Driver Modules that provide 7 switchable ground outputs for operating solenoids, relays, telltales, and other devices. Each of these ground outputs has an internal fault line that feeds back to the PCMs microprocessor. When the output is OFF, the output driver should receive the 12 volts fed to the solenoid, relay, etc. When the output is ON, it should receive 0 volt since it is grounding the output. If it receives 0 volt when the output is OFF or 12 volts when the output is ON, it sets the fault line low.

OBDII Code P1646 Cadillac - EVAP Vent Solenoid Output Circuit - AutoCodes.com — P1646 Cadillac Code - EVAP Vent Solenoid Output Circuit

What does this mean?

What are the Possible Causes of the DTC P1646 Cadillac?

Faulty EVAP Vent Solenoid
EVAP Vent Solenoid harness is open or shorted
EVAP Vent Solenoid circuit poor electrical connection

How to Fix the DTC P1646 Cadillac?

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 P1646 Cadillac 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.