Is a relearn necessary when replacing the front oil seal?

Good morning,

Since you will be removing the harmonic balancer, yes, it will need to be relearned.

I attached the procedure below for you to follow for the re-learn.

Roy

IMPORTANT:
The scan tool monitors certain component signals to determine if all the conditions are met to continue with the procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool monitors the following components:
Crankshaft position (CKP) sensors activity-If there is a CKP sensor condition, refer to the applicable DTC.
Camshaft position (CMP) signal activity-If there is a CMP signal condition, refer to the applicable DTC.
Engine coolant temperature (ECT)-If the engine coolant temperature is not warm enough, idle the engine until the engine coolant temperature reaches the correct temperature.
The CKP system variation learn procedure is also required when the following service procedures have been performed, regardless of whether DTC P0315 is set:
An engine replacement
A powertrain control module (PCM) replacement
A crankshaft balancer replacement
A crankshaft replacement
A CKP sensor replacement
Any engine repairs which disturb the crankshaft to CKP sensor relationship.

1. Install a scan tool.
2. Monitor the PCM for DTCs with a scan tool. If other DTCs are set, except DTC P0315, refer to Diagnostic Trouble Code (DTC) List - Vehicle for the applicable DTC. See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions
3. With a scan tool, select the CKP variation learn procedure and perform the following:
1. Observe fuel cut-off for applicable engine.
2. Block drive wheels.
3. Set parking brake.
4. DO NOT apply brake pedal.
5. Cycle ignition from OFF to ON.
6. Apply and hold brake pedal for the duration of the procedure.
7. Start and idle engine.
8. Turn the air conditioning (A/C) OFF.
9. The vehicle must remain in Park or Neutral.
10. Accelerate to wide open throttle (WOT).

IMPORTANT:
The engine should not accelerate beyond the calibrated fuel cut-off RPM value noted in step 3.1. Release the throttle immediately if the value is exceeded.
While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine responds to throttle position after the learn procedure is complete.

4. The scan tool displays Learn Status: Learned this ignition. If the scan tool indicates that DTC P0315 ran and passed, the CKP variation learn procedure is complete. If the scan tool indicates DTC P0315 failed or did not run, refer to DTC P0315. If any other DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for the applicable DTC. See: A L L Diagnostic Trouble Codes ( DTC ) > P Code Charts > P0315 See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions
5. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully in order to store the CKP system variation values in the PCM memory.