What does code P1740 mean?

P1740: Lockup/Select Switching Solenoid Valve Malfunction (Mitsubishi CVT)

Severity: medium

What it means: On Mitsubishi CVTs, the transmission computer saw that the lockup/select switching solenoid valve isn't getting the right current, from an open or short circuit.

Safe to drive? Usually drivable short distances, but the transmission may go into a fail-safe mode with a hard shift into drive or reverse. Get it checked soon.

Common symptoms

Check-engine light
Shift shock going from neutral to drive or reverse
Transmission warning light
RPM bouncing at a stop

Likely causes, ranked

CVT computer (TCM) setting or fault; Mitsubishi bulletin TSB-20-23C-001 replaces it on 2015–2017 Outlander SportShop
Faulty lockup/select switching solenoid valve (part of the valve body)Shop
Damaged wiring harness or connectorsShop

Vehicle-specific notes

2015–2017 Mitsubishi Outlander Sport: Mitsubishi bulletin TSB-20-23C-001 (October 2020) says the check-engine light comes on and the transmission shifts hard from neutral to drive or reverse because of a fail-safe, storing P1740. Dealers replace the CVT computer with an updated part that changes how it monitors the solenoid voltage. A 2015 Outlander Sport owner on EvolutionM had an intermittent transmission light and P1740 after the warranty ran out, with the rpm bouncing at stops. Read the full answer · Source

DIY or shop?

Shop. The fix is diagnosed with a Mitsubishi-level scan tool and may mean a new CVT computer or valve body.

Before you replace parts

Ask the dealer to check your VIN for TSB-20-23C-001 and any open recalls. A bulletin isn't a recall, but it tells the dealer the known fix.
Read all stored codes and freeze-frame data, not just this one.
Inspect the CVT wiring and connectors before buying parts.
Make sure any CVT fluid service used Mitsubishi's specified fluid.
Clear the code only after a repair, then confirm it stays off.

Safety / mechanic note

Verify with a mechanic. A hard shift or a transmission in fail-safe mode can surprise you in traffic. A code points to a circuit or system, not always a specific part.