AutoCodes – GMC – P1628 GMC

P1628 GMC Code - Powertrain Control Module Engine Control Temperature Pullup Resistor Conditions

Quick Answer

With the cold engine startup, the Powertrain Control Module (PCM) detects a fault in the PCM pullup resistor used to revise Engine Control Temperature (ECT) resolution in engine operation. Common causes include Faulty Engine Control Temperature Pullup Resistor, Engine Control Temperature Pullup Resistor harness is open or shorted, Engine Control Temperature Pullup Resistor 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: P1628 GMC indicates Powertrain Control Module Engine Control Temperature Pullup Resistor Conditions.
Common causes: Common causes include Faulty Engine Control Temperature Pullup Resistor, Engine Control Temperature Pullup Resistor harness is open or shorted, Engine Control Temperature Pullup Resistor 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 6,506

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Sep 02, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1628 GMC Description

With the cold engine startup, the Powertrain Control Module (PCM) detects a fault in the PCM pullup resistor used to revise Engine Control Temperature (ECT) resolution in engine operation.

OBDII Code P1628 GMC - Powertrain Control Module Engine Control Temperature Pullup Resistor Conditions - AutoCodes.com — P1628 GMC Code - Powertrain Control Module Engine Control Temperature Pullup Resistor Conditions

What does this mean?

What are the Possible Causes of the DTC P1628 GMC?

Faulty Engine Control Temperature Pullup Resistor
Engine Control Temperature Pullup Resistor harness is open or shorted
Engine Control Temperature Pullup Resistor circuit poor electrical connection

How to Fix the DTC P1628 GMC?

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 P1628 GMC 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.