P1737 — 2-3 Shift Malfunction

What are the symptoms of P1737?

Drivers most often notice: the affected system operates intermittently or not at all, increased fuel consumption in some cases, possible limp mode depending on the affected component, Check Engine Light on.

How do I diagnose P1737 myself?

Start with a scan: confirm P1737, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the 2-3 shift, and verify the suspect component against live data before buying parts.

How much does it cost to fix P1737?

Repair wiring or connectors — $80–$250; Control module repair — $300–$1,000; Replace the faulty sensor or actuator — $150–$500. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

Will P1737 clear itself?

Sometimes P1737 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What is the most common cause of P1737?

The most common causes are: blown fuse feeding the circuit, control module driver fault, open or shorted wiring in the circuit.

The engine control module (ECM) logs trouble code P1737 when its self-test detects a problem with the 2-3 shift circuit. In plain language, this is a 2-3 shift malfunction — the transmission is not executing the upshift from second to third gear the way the computer expects. P1737 falls into the powertrain category of OBD2 codes, meaning it touches both the engine and the transmission control systems.

Unlike a straightforward electrical circuit code, P1737 is classified as a general malfunction code. That distinction matters: the fault could be inside the component itself, or it could be inside the control module. Electrical testing comes first, but be prepared to consider either side. The ECM will not illuminate the Check Engine light on a single bad reading. It watches for the same fault condition to recur under specific driving conditions before confirming the code. The freeze frame data stored alongside P1737 captures engine load, RPM, coolant temperature, and vehicle speed at the moment of failure — use those numbers to replicate the problem during testing.

Common Symptoms of P1737

When P1737 is active, the transmission may hesitate, slip, or fail to complete the 2-3 upshift entirely. In some vehicles the problem shows up only under load or at certain speeds. You may notice the engine revving higher than normal before the shift finally engages, or the car may feel sluggish during acceleration. Increased fuel consumption is a frequent side effect because the engine works harder when the transmission cannot shift properly. Depending on the vehicle and the exact nature of the fault, the ECM may impose a limp-home mode that limits gears or disables certain functions to protect the drivetrain. Of course, the Check Engine Light will be on.

What Causes P1737?

The root cause of P1737 typically falls into one of three areas: the transmission internals, the electronics that control it, or the wiring between the two. Starting with the most common culprits, a failed sensor or actuator in the 2-3 shift circuit — such as a shift solenoid, pressure switch, or speed sensor — is frequently responsible. Corroded, loose, or damaged connectors and poor ground connections can also create intermittent faults that trigger this code. Wiring problems, including chafed insulation, open circuits, or shorts, prevent the control module from getting a clean signal and will cause the self-test to fail. On the other end of the spectrum, an internal fault within the 2-3 shift mechanism itself — a mechanical binding or wear issue — can produce the same result. Less frequently, a software calibration error or a fault in the control module's output driver will set P1737 even when all the wiring and sensors check out fine.

How to Diagnose P1737

1. Connect a quality OBD2 scanner, confirm that P1737 is stored, and record the freeze frame data. Those snapshot conditions — load, RPM, temperature, vehicle speed — tell you exactly what was happening when the module detected the fault, and they guide every step that follows.
2. Pull all stored and pending codes. Related codes often point to the true culprit; for example, an upstream sensor failure can cascade and produce a generic 2-3 shift malfunction code. Check manufacturer technical service bulletins (TSB) for your make and model — certain P1737 issues have known factory remedies or software updates already published.
3. Perform a thorough visual inspection of the wiring harness and connectors tied to the 2-3 shift circuit. Look for broken insulation, corrosion, bent pins, and any signs of moisture intrusion. Pay close attention to areas where the harness flexes or passes near hot components.
4. If your scan tool supports bidirectional controls, run the module's actuator test for the 2-3 shift circuit. A solenoid or actuator that ignores a direct command is confirmed faulty and warrants replacement.
5. With the connector unplugged, measure reference voltage, ground integrity, and signal continuity at the component harness. Compare your readings against the manufacturer's specifications in a service manual.
6. Wiggle-test the harness while monitoring live data on the scanner. Any signal dropout or fluctuation during physical manipulation of the wiring points directly to a broken wire or intermittent connection.

Repair Options for P1737

Work from the outside in — tackle the cheap and common problems before moving to expensive components. Wiring repair or connector replacement typically runs $80 to $250. If the control module itself is diagnosed as the culprit — which requires ruling out every external component first — module repair or replacement falls in the $300 to $1,000 range depending on whether you go with a rebuilt unit or dealer service. Replacing a faulty sensor or actuator, such as a shift solenoid or transmission input/output speed sensor, generally costs $150 to $500 including parts and labor.

Total Cost to Fix P1737

The actual spend depends entirely on which part is at fault. A loose connector cleaned and reseated costs little more than诊断 time. Rewiring a damaged harness runs $80–$250 at most independent shops. A new or remanufactured control module pushes the bill to $300–$1,000. A replacement solenoid or sensor sits in the middle at $150–$500. Across all scenarios, expect to pay somewhere between $80 and $1,000 for P1737. An accurate diagnosis before buying any parts is the single most effective way to keep costs under control — the worst-case scenario is rarely the first thing to check.

Can You Drive with P1737?

Most vehicles remain drivable when P1737 is stored, though you may notice poor acceleration, higher fuel consumption, or the transmission staying in a lower gear. If the ECM has entered limp mode, performance will be noticeably reduced and you should plan to have the vehicle inspected soon. However, if the car stalls, refuses to start, or the Check Engine light is accompanied by brake or steering warnings, treat it as a urgent situation and avoid further driving until the cause is identified.

Related OBD2 Codes

• P1700: Wastegate Solenoid Circuit Malfunction
• P1701: Turbo Pressure Control Solenoid Circuit Malfunction
• P1702: Turbo Control Solenoid Circuit Malfunction
• P1703: Turbo Charge Control Circuit Malfunction
• P1704: Turbo Charge Relief Circuit Malfunction
• P1705: Transmission Indeterminate Failure (Failed to Neutral)