Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / P1728 — Transmission Slip Error

P1728 — Transmission Slip Error

Detailed page for trouble code P1728.

34,405codes
59brands
11,914generic
22,491specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

P1728

LINCOLN P — Powertrain

Transmission Slip Error

Brand: LINCOLN
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Low or deteriorated transmission fluid
  • Incorrect transmission fluid type
  • Worn friction clutch packs or bands
  • Faulty shift solenoid(s) or valve body
  • Low hydraulic/line pressure (pump or leaks)
  • Faulty turbine/input or output speed sensor

Symptoms

  • Transmission slip under acceleration (engine revs rise without corresponding vehicle speed increase)
  • Delayed or harsh engagement when shifting
  • Erratic shift patterns or failure to hold gear
  • Transmission/Check Engine light ON (MIL/TMIL)
  • Loss of power or poor drivability
  • Transmission overheating warning or elevated fluid temp

What to check

  • Read and record all stored and pending codes and freeze-frame data with a capable scan tool
  • Verify transmission fluid level, color, smell, and correct type per manufacturer
  • Road test with scan tool monitoring input speed, output speed, gear commanded vs actual, line pressure if available
  • Inspect wiring harnesses and connectors for damage, corrosion, or looseness around TCM, solenoids, and speed sensors
  • Check for TSBs, software updates, and confirmed fixes for this code/model year
  • Perform visual inspection for external leaks and condition of transmission cooler lines

Signal parameters

  • Engine RPM
  • Transmission input/turbine speed (TSS)
  • Transmission output/vehicle speed sensor (OSS/VSS)
  • Calculated gear ratio (input speed / output speed)
  • Commanded gear vs actual gear
  • Line or governor pressure (where supported by scan tool or gauge)

Diagnostic algorithm

  1. Retrieve freeze-frame and all active/pending codes. Note conditions when fault set (gear, RPM, load, temp).
  2. Visually inspect connectors and wiring for damage at TCM, speed sensors and solenoid pack. Repair any faults.
  3. Check transmission fluid level and condition; correct level and replace fluid/filter if contaminated or unknown history.
  4. Using a scan tool, monitor input and output speeds while road testing under load. Confirm difference/ratio out of spec when code sets.
  5. Verify shift solenoid operation: command solenoids on/off and observe changes in pressure/ration and solenoid feedback. Replace if nonfunctional or sticking.
  6. If low pressure suspected, perform hydraulic pressure tests (line and apply pressures) per service manual. Repair pump, valve body, or seals as required.
  7. If torque converter suspected, perform stall test and TCC function checks; consider bench testing or replacement if internal failure likely.
  8. If mechanical wear is suspected (worn clutch packs/plates), remove pan and inspect for debris, burnt friction material, and check valve body/solenoid condition.
  9. Apply any manufacturer software updates to the TCM and clear codes. Re-test to confirm repair.
  10. If fault persists after above checks, consult technical service literature and consider module testing/replacement as a last resort.

Likely causes

  • Low or contaminated transmission fluid
  • Worn clutches or friction material
  • Sticking or failed shift solenoid(s) or valve body issue
  • Low line pressure due to pump wear or internal leak
  • Faulty speed sensor or poor sensor signal to TCM

Fault status

⚠️ Status
TCM detected transmission slip: commanded gear/ratio not achieved. Condition may be due to hydraulic pressure loss, worn clutches, solenoid/valve body or sensor/electrical faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 2.0 - 6.0 hours

Similar codes

P0700 P0715 P0720 P0725 P0730 P0731
166

Browse 166 LINCOLN manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LINCOLN

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .