OBD-II code · Powertrain (generic, extended)
P257C Vacuum Reservoir Control Circuit High
The vacuum reservoir control circuit reads stuck high — short to battery voltage or open coil. The driver cannot pull the line low to actuate the valve/motor.
Is it safe to drive with P257C?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyControl wire shorted to battery voltage
- PossibleOpen coil
- Less likelyConnector pins corroded - high contact resistance
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–2 h
- Emissions test
- Usually unaffected
- Parts involved
- Vacuum Reservoir Control Valve
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.