4L80E Codes Cheat Sheet: Codes and Fixes

This is your 4L80E code reference. Each code with what it means, what fails, and how to fix it. Bookmark this.

How to use this guide

When you have a code:

Before buying parts:

P0700: TCM Request MIL

What it means:

  • Generic "TCM has a problem"
  • Pull additional codes

Fix:

  • Read additional TCM codes
  • Address specific code first

P0717: Input Speed Sensor Circuit No Signal

What it means:

  • ISS not communicating
  • TCM can't see input speed

Diagnosis:

Fix:

  • Replace ISS: $50-150
  • Or repair wiring: minimal cost

P0722: Output Speed Sensor Circuit No Signal

What it means:

  • OSS not communicating
  • Vehicle speed unknown

Diagnosis:

  • Same procedure as ISS
  • Different sensor location

Fix:

  • Replace OSS: $50-150
  • Or repair wiring

P0723: Output Speed Sensor Intermittent

What it means:

  • OSS dropping signal randomly

Fix:

  • Often connector issue
  • Sometimes failing sensor
  • Replace sensor or repair connector

P0731: Gear 1 Incorrect Ratio

What it means:

  • 1st gear slipping or sensor mismatch
  • Often clutch issue

Diagnosis:

Fix:

P0732: Gear 2 Incorrect Ratio

What it means:

  • 2nd gear slip
  • Often intermediate band wear

Diagnosis:

Fix:

  • HD intermediate band
  • Sometimes full rebuild
  • $200-2,500

P0733: Gear 3 Incorrect Ratio

What it means:

  • 3rd gear slip
  • Direct clutch wear typical

Diagnosis:

Fix:

  • Direct clutch rebuild
  • HD upgrade recommended
  • $1,500-3,500

P0734: Gear 4 Incorrect Ratio (Overdrive)

What it means:

  • 4th gear slip
  • OD-specific apply issue

Diagnosis:

  • Pan inspection
  • Specific to OD clutch pack

Fix:

  • OD rebuild
  • $1,500-3,500

P0741: TCC Stuck Off

What it means:

  • TCC commanded on but not engaging
  • Or slipping when commanded

Diagnosis:

Fix:

P0742: TCC Stuck On

What it means:

  • TCC engages and won't release
  • Engine stalls at stop

Diagnosis:

  • TCC solenoid stuck
  • Or apply piston damaged

Fix:

  • Solenoid replacement
  • Or full rebuild if piston damaged

P0748: Force Motor Electrical (PWM Pressure)

What it means:

  • Force motor (line pressure PWM) failure

Diagnosis:

Fix:

  • Force motor replacement: $100-300
  • Or full solenoid pack: $250-450

P0751: Shift Solenoid A Performance

What it means:

  • Shift solenoid A not working correctly

Diagnosis:

  • Resistance test
  • Pressure test for line pressure issue

Fix:

P0753: Shift Solenoid A Electrical

What it means:

  • Electrical fault in shift solenoid A circuit

Diagnosis:

  • Wiring check
  • Solenoid resistance

Fix:

  • Often wiring repair
  • Sometimes solenoid replacement

P0756: Shift Solenoid B Performance

What it means:

  • Shift solenoid B not working correctly

Diagnosis and fix:

  • Same as P0751 for solenoid B

P0758: Shift Solenoid B Electrical

What it means:

  • Electrical fault in shift solenoid B

Fix:

  • Same approach as P0753

P0785: Shift/Timing Solenoid Malfunction

What it means:

  • 3-2 shift solenoid issue

Fix:

  • Solenoid pack replacement typical

P0815: Up Shift Switch

What it means:

  • Driver-input switch fault

Fix:

  • Often button on shift handle
  • Wiring check

P0860: Gear Shift Module Communication

What it means:

  • TCM communication issue

Diagnosis:

  • More serious
  • Check TCM connections
  • Possible TCM replacement

P1810: TFP Valve Position Switch

What it means:

  • Pressure switch manifold issue
  • Specific to 4L80E

Diagnosis:

  • Check PSM
  • Often inside trans pack

Fix:

  • PSM replacement
  • Or full pack: $250-500

P1860: TCC PWM Solenoid Electrical

What it means:

  • TCC PWM circuit issue

Fix:

P1870: TCC Slip Excessive

What it means:

  • TCC slipping (very common)

Diagnosis:

Fix:

  • Solenoid first (cheaper try)
  • Then rebuild with HD apply piston

Multi-code scenarios

Multiple shift solenoid codes:

Multiple gear ratio codes:

Speed sensor + gear codes:

  • Sensor issue causing gear codes
  • Fix sensor first

TCC codes + pressure switch:

  • Internal pressure issue
  • Pack-level service

When NOT to just clear codes

Don't clear if:

  • Haven't fixed underlying issue
  • Code returns immediately
  • Pan shows damage

Read our transmission warning signs

Cost summary

Easy fixes ($50-300):

  • Single sensor replacement
  • Wiring repair
  • Connector cleaning

Medium fixes ($200-800):

Expensive fixes ($1,500-3,500):

  • Full rebuild
  • Multiple clutch packs
  • Hard parts replacement

Code priority order

Address first:

  • Speed sensors (cheap, common)
  • Wiring issues
  • Connectors

Then:

  • Single solenoid issues

Then:

  • Pack-wide failures

Then:

  • Internal rebuild needs

Don't skip pan inspection:

Need 4L80E parts based on your codes? Shop our 4L80E catalog. Sensors, solenoids, packs, rebuild kits. Free shipping over $70.

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