What Does P1742 Mean?
The transmission control module is receiving incorrect or missing input signals required for automatic transmission diagnosis and operation. This typically involves speed sensors, pressure sensors, or other transmission-related input devices.
Common Causes
35%
Failed vehicle speed sensor or transmission output speed sensor
25%
Faulty transmission input speed sensor
20%
Wiring or connector problems in sensor circuits
15%
Failed transmission fluid pressure sensor
5%
TCM/PCM internal fault or software issue
Diagnostic Steps
1
Step 1: Monitor live data stream for all transmission input sensors (speed sensors, pressure sensors, switches)
2
Step 2: Check for erratic or missing signals during test drive or on lift with wheels spinning
3
Step 3: Inspect sensor connectors and wiring for damage, corrosion, or oil contamination
4
Step 4: Test sensor resistance and voltage output against manufacturer specifications
5
Step 5: Verify proper sensor installation and air gap where applicable
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
The transmission control module is receiving incorrect or missing input signals required for automatic transmission diagnosis and operation. This typically involves speed sensors, pressure sensors, or other transmission-related input devices.
The most common cause of P1742 (Auto Trans Diagnosis Input Signal Malfunction) is: Failed vehicle speed sensor or transmission output speed sensor
Typical repair costs for P1742 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
May cause harsh shifting, failure to shift properly, or transmission to enter limp mode. Vehicle should be driven cautiously until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1742 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Automatic Transmission
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
