AutoCodes – Chevrolet – P1623 Chevrolet

P1623 Chevrolet Code - Transmission Fluid Temperature Sensor Pullup Resistor Circuit Conditions

Quick Answer

With the cold engine startup completed, engine running, the Powertrain Control Module (PCM) detects a fault in the PCM pull-up resistor used to revise Engine Coolant Temperature (ECT) resolution throughout the complete engine operating range. Common causes include Faulty Transmission Fluid Temperature (TFT), Transmission Fluid Temperature (TFT) harness is open or shorted, Transmission Fluid Temperature (TFT) 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: P1623 Chevrolet indicates Transmission Fluid Temperature Sensor Pullup Resistor Circuit Conditions.
Common causes: Common causes include Faulty Transmission Fluid Temperature (TFT), Transmission Fluid Temperature (TFT) harness is open or shorted, Transmission Fluid Temperature (TFT) 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 4,550

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 01, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1623 Chevrolet Description

OBDII Code P1623 Chevrolet - Transmission Fluid Temperature Sensor Pullup Resistor Circuit Conditions - AutoCodes.com — P1623 Chevrolet Code - Transmission Fluid Temperature Sensor Pullup Resistor Circuit Conditions

What does this mean?

What are the Possible Causes of the DTC P1623 Chevrolet?

Faulty Transmission Fluid Temperature (TFT)
Transmission Fluid Temperature (TFT) harness is open or shorted
Transmission Fluid Temperature (TFT) circuit poor electrical connection

How to Fix the DTC P1623 Chevrolet?

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 P1623 Chevrolet 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.

Need more information about the P1623 Chevrolet code?

Need more information on how to fix the P1623 Chevrolet code? Get Access to Factory Service Manuals

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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 P1623 Chevrolet Code

What does the OBDII code P1623 mean for a Chevrolet vehicle?

P1623 indicates an issue with the transmission fluid temperature sensor pullup resistor circuit. This means the engine control module (ECM) has detected a problem with the circuit that helps measure transmission fluid temperature.

What are the common symptoms of code P1623 in a Chevrolet?

Symptoms may include erratic or incorrect transmission fluid temperature readings, harsh or delayed shifting, illuminated check engine light, and potential transmission overheating.

What causes the P1623 code in Chevrolet vehicles?

Common causes include a faulty transmission fluid temperature sensor, damaged or corroded wiring, poor electrical connections, or a malfunctioning ECM.

How do I diagnose the P1623 code in my Chevrolet?

Start by checking the transmission fluid temperature sensor and its wiring for damage, corrosion, or disconnections. Use a multimeter to test the sensor’s resistance and inspect the ECM for faults.

Can I drive my Chevrolet with the P1623 code?

While the vehicle may still be drivable, it’s not recommended, as unresolved issues with the transmission fluid temperature sensor circuit could lead to transmission overheating or damage over time.

How do I fix the P1623 code on a Chevrolet?

Repairs may involve replacing the transmission fluid temperature sensor, repairing damaged wiring or connectors, or, in rare cases, replacing the ECM if it’s determined to be the root cause.

How much does it cost to fix the P1623 code?

The repair cost depends on the cause, but replacing a transmission fluid temperature sensor typically costs between $100 and $300, including parts and labor. Wiring repairs or ECM replacement may cost more.

Can low transmission fluid cause the P1623 code?

Low transmission fluid levels are unlikely to cause this code directly, but they can lead to overheating, which may exacerbate sensor or circuit issues.

How can I prevent the P1623 code from occurring?

Regular maintenance, including checking transmission fluid levels, inspecting wiring for damage, and ensuring the sensor is functioning properly, can help prevent this code.

Does the P1623 code require a transmission rebuild?

In most cases, a transmission rebuild is not necessary to fix the P1623 code. The issue is typically related to the sensor, wiring, or ECM, rather than the internal mechanics of the transmission.