01 You Can Tell A Lot About A Car By Listening To Its Engine I… • 02 Unlocking the Skies: A Comprehensive Guide to Thriving in t… • 03 Stellantis Issues Major Recall for 211,000 Vehicles Over AB… • 04 At What Mileage Do Most Cars Start Having Issues? • 05 Why Tire Businesses Always Stay Profitable • 06 What Causes Your RPM to Go Up and Down When You Brake? Find… • 07 How Fast Can a Car Go in Reverse? • 08 The Ex-Race Engineer Tells Us The Truth About Turbo Longevi… • 09 The 30-60-90K Maintenance Schedule Explained: What Your Dea… • 10 U0003, U0004, U0005, U0006, U0007, and U0008: High Speed CA… •

DTC codes / Nissan codes / P1758

P1758 · NissanTCM A/T Lockup Solenoid Valve "B" Fault

P1758 on Nissan vehicles means the Transmission Control Module (TCM) has detected an electrical fault in the lockup solenoid valve 'B' circuit inside the automatic transmission. The TCM monitors the solenoid's current draw and response, and it sets this code when the circuit is open, shorted, or the solenoid fails to actuate as commanded.

SystemPowertrain
Code typeNissan specific
SeverityMedium
Fix difficultyProfessional
AreaTransmission

Symptoms you may notice

  • Illuminated Check Engine Light or Transmission Warning Light on the dashboard
  • Transmission may stay in a default gear or fail to engage lockup, causing poor fuel economy at highway speeds
  • Harsh or delayed shifting, especially when the torque converter should lock up
  • Engine RPM may flare or surge at steady highway speeds because the lockup clutch is not applying
  • Often no symptoms besides the warning light, especially if the fault is intermittent
  • Possible limp mode with reduced power and limited gear selection in some Nissan models

Common causes, most likely first

  1. Failed lockup solenoid valve 'B' inside the transmission valve body
  2. Damaged or corroded wiring harness connector at the transmission solenoid pack
  3. Open or shorted wire in the lockup solenoid circuit between the TCM and the transmission
  4. Contaminated transmission fluid causing solenoid sticking or poor electrical contact
  5. Faulty Transmission Control Module (TCM) or poor TCM ground connection
  6. Internal valve body wear or debris blocking the lockup solenoid hydraulic circuit

How to diagnose and fix it

  1. Check transmission fluid level and condition; top off or replace fluid if dark or contaminated
  2. Inspect the transmission wiring harness and solenoid pack connector for corrosion, chafing, or loose pins
  3. Measure resistance of the lockup solenoid valve 'B' at the transmission connector and compare to Nissan specifications
  4. Test the solenoid circuit for continuity and short-to-ground between the TCM and the transmission
  5. If electrical tests pass, remove the valve body and inspect the lockup solenoid for mechanical sticking or debris
  6. Replace the faulty lockup solenoid valve 'B' or the complete solenoid pack if individual replacement is not available
  7. Clear the code and perform a road test to verify lockup engagement and confirm the code does not return

Lockup Solenoid Faults Often Misdiagnosed

  • A P1758 code can be set by a simple loose or corroded connector at the transmission, so always inspect the harness before condemning the solenoid.
  • On many Nissan models, the lockup solenoid is part of the valve body assembly, and replacing just the solenoid may not be possible without replacing the entire valve body.
  • Intermittent P1758 codes often appear after the transmission reaches operating temperature, when electrical resistance changes in a failing solenoid.
  • A faulty TCM ground or low battery voltage can mimic a lockup solenoid fault, so check charging system and grounds before replacing parts.
  • Driving with P1758 for extended periods can cause torque converter clutch shudder and eventually damage the torque converter or transmission.

Can I keep driving with P1758?

You can usually drive short distances to a repair shop, but avoid highway speeds and heavy loads because the lockup clutch may not engage, causing overheating and poor fuel economy. If the transmission enters limp mode or shifts harshly, stop driving and have it towed to prevent further damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Nissan vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage