Engine-CodesGMC – P1674 GMC

P1674 GMC Code - Tachometer Control Circuit

Quick Answer

The P1674 diagnostic trouble code (DTC) for GMC vehicles relates to the tachometer control circuit. Common causes include Faulty tachometer sensor, Damaged wiring or connectors in the tachometer circuit, ECM malfunction. 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
P1674 GMC indicates Tachometer Control Circuit.
Common causes
Common causes include Faulty tachometer sensor, Damaged wiring or connectors in the tachometer circuit, ECM malfunction.
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.
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P1674 GMC Description

The P1674 diagnostic trouble code (DTC) for GMC vehicles relates to the tachometer control circuit. This code is triggered when the Engine Control Module (ECM) detects a problem with the tachometer signal circuit. The tachometer is responsible for displaying the engine's RPM (Revolutions Per Minute) on the instrument cluster. When this circuit malfunctions, it can lead to inaccuracies in RPM readings or a complete failure of the tachometer display.

OBDII Code P1674 GMC - Tachometer Control Circuit
P1674 GMC Code - Tachometer Control Circuit

Common Causes of P1674 GMC

  1. Faulty tachometer sensor
  2. Damaged wiring or connectors in the tachometer circuit
  3. ECM malfunction
  4. Poor electrical connection
  5. Engine speed sensor issues

Symptoms of P1674 GMC

  1. Inaccurate or erratic tachometer readings
  2. Tachometer needle fluctuating unexpectedly
  3. Tachometer not working at all
  4. Engine misfires or hesitation
  5. Check Engine Light illuminated

How to Fix P1674 GMC

  1. Diagnose the tachometer control circuit using a scan tool to pinpoint the exact cause of the issue.
  2. Inspect the wiring and connectors for any damage or corrosion. Repair or replace as necessary.
  3. Test the tachometer sensor for proper functionality. Replace if faulty.
  4. Check the ECM for any signs of malfunction. Reset or replace if needed.
  5. Clear the DTC and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P1674 GMC

The typical repair costs for addressing the P1674 code related to the tachometer control circuit can vary depending on the extent of the issue and the specific components that need to be replaced. On average, the parts for this repair could range from $50 to $200, while the labor costs may add another $100 to $200 to the total bill. Keep in mind that diagnosis time and labor rates at auto repair shops can fluctuate, so it's advisable to inquire about local rates for a more accurate estimate.

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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.

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