Chain noise at startup from your 2020 Subaru Legacy's Lineartronic CVT can be concerning, though some noise may be normal as the system pressurizes. Understanding the difference between normal and abnormal startup sounds helps determine if action is needed.
Normal Startup CVT Behavior
When the engine starts, the CVT pump needs time to build pressure and circulate fluid. During this brief period (a few seconds), some noise from the chain and pulleys can occur. A quick rattle or whir that disappears almost immediately may be normal.
Abnormal Startup Noise
Noise lasting more than a few seconds after startup. Grinding or metallic sounds rather than brief rattle. Noise accompanied by vibration in the vehicle. Startup noise that has developed or worsened over time. Any noise accompanied by warning lights or codes.
Code P0730 and Startup Noise
P0730 indicates incorrect ratio, which during startup could mean the CVT is struggling to establish proper operation. If codes set during startup, there's a functional problem beyond just noise.
Why Chain Noise Develops
Chain stretch allows more slack during unpressurized startup. Pulley surface wear changes chain engagement. Low fluid level delays pressurization. Pump wear slows pressure buildup. Each condition allows more noise before normal operation establishes.