2021 Hyundai Tucson P1326 DTC After ECU Update TSB

Hyundai Technical Service Bulletin (TSB) 24-EM-002H addresses a specific concern for 2016-2021 Hyundai Tucson (TL) 2.0L vehicles. Owners of these vehicles may find that the Diagnostic Trouble Code (DTC) P1326 persists even after a prior Engine Control Unit (ECU) software update, specifically one performed under TSB 22-01-028H-1 (Service Campaign 966).

This bulletin provides a detailed service procedure to properly diagnose and resolve the continued Hyundai Tucson P1326 issue, ensuring the KSDS Engine Monitoring Logic functions correctly.

Symptoms

The primary symptom indicating this issue is the continued illumination of the Malfunction Indicator Lamp (MIL) with Diagnostic Trouble Code (DTC) P1326. This occurs even after the vehicle has already received an ECU update related to the KSDS Engine Monitoring Logic.

Fault Codes / DTCs

This TSB specifically addresses the following diagnostic trouble code:

Code	Description
P1326	KSDS Engine Monitoring Logic

Important Warnings

Hyundai outlines several critical warnings for technicians performing this service:

• "Do not perform ECU update without completing the ENGINE MECHANICAL PRE-CHECK." This step is crucial to ensure underlying mechanical issues are not contributing to the DTC P1326.
• "Not all vehicles will require an ECU update for final repair." The ECU update is only necessary if the P1326 DTC persists after all mechanical pre-checks and retesting.
• GDS Vehicle Battery Low Voltage Warning: "If voltage is below 12 volts as per the below GDS warning, then select Back and attach a battery charger to ensure an adequate battery state of charge for reliable update results. Turn ignition back on, and then retry the ECU update again." This prevents potential issues during the ECU update process.
• If "No DTC P1326 observed" after initial inspections and retesting, the "Service procedure is now complete, no other steps required."
• If "Continued DTC P1326 observed" after initial inspections and retesting, then "Continue to next step for manual ECU update process."

Diagnosis / Trigger Conditions

Before any ECU update, a thorough "ENGINE MECHANICAL PRE-CHECK" must be performed using a GDS scan tool to confirm the presence of DTC P1326 and rule out other contributing factors. This check includes:

• Engine Oil Condition: Ensure engine oil is clean, within the last 3,000 miles/6 months of maintenance, and topped off to the 'F' mark.
• Coolant Level: Verify coolant level is adequate. Top off or replace as needed if low or in poor condition.
• Spark Knock/Pre-ignition: Check for spark knock or pre-ignition during acceleration and throttle tip-in. This could be due to fuel quality/contamination or combustion chamber deposits. If resolved, reset engine adaptive values.
• Knock Sensor Installation Quality and Connection: Confirm the knock sensor is properly installed on a cleaned casting surface with the correct torque. Inspect the connection to the engine harness for corrosion or intermittent contact. Clean the 2-pin connection points with electrical contact cleaner and compressed air.
• Bearing Clearance Test (BCT): The engine must pass the Bearing Clearance Test as per TSB 22-01-023H-2 (Service Campaign T6G). Any abnormal engine noises should be diagnosed and resolved, comparing with a known good vehicle if necessary.

Repair Procedure Summary

If, after completing the comprehensive engine mechanical pre-check and retesting, the Hyundai Tucson P1326 DTC continues to appear, a manual ECU update is required. The process involves:

1. Confirm DTC P1326: Use a GDS scan tool to ensure the DTC P1326 is present.
2. Perform Engine Mechanical Pre-Check: Complete all inspections as detailed above and correct any issues found.
3. Retest Vehicle: After all adjustments and repairs, retest the vehicle with a brief test drive to see if DTC P1326 duplicates.
4. Prepare for ECU Update: If P1326 persists, capture the ECU ROM ID. Refer to HTSS "Fix It Right" under "General Information – Special Instructions" for guidance.
5. Manual ECU Update: Perform the ECU update using a GDS tool. Techline will review and approve the ECU Update, providing a password for the appropriate NEW ECU ROM ID. Ensure battery voltage is sufficient before starting the update.
6. Cycle Ignition and Clear DTCs: After the ECU upgrade shows 100% completion, cycle the ignition key to OFF for at least 30 seconds to reset the control unit. Then, perform an all-systems fault code search and erase any incidental DTCs.

Required Tools or Parts

• GDS Scan Tool: For confirming DTCs, performing diagnostics, and executing the ECU update.
• Battery Charger: Essential to maintain adequate battery voltage during the ECU update process.
• ECU ROM IDs: Specific ROM IDs are listed in the TSB for various vehicle configurations (MY, 2WD/4WD, IMMO type). Technicians must verify the existing ECM ROM ID and update to the corresponding new ROM ID. An example casual part number for warranty claims is 39133-2ETA6.

Warranty Information

For warranty claims related to this ECU update, the following details apply:

• Operation Code: 10D021RE
• Operation: DTC Inspection + ECU Update
• Op. Time: 0.4 Man-Hours
• Casual Part: 39133-2ETA6
• Nature Code: I11
• Cause Code: ZZ3

Claims should be submitted as "Campaign" type. If a part requiring replacement is under warranty, a separate claim should be submitted. If out of warranty, a Prior Approval request for goodwill consideration is needed.

Source: NHTSA ID 10252363