P257A code meaning
Vacuum Reservoir Control Circuit/Open
Powertrain system Generic code P25xx codes Check engine light
What P257A means
P257A is an output fault on the control line of the vacuum reservoir, usually a solenoid or switching valve the engine computer uses to connect, isolate or vent a vacuum storage tank. Such tanks occur mainly on diesels whose EGR valves, turbocharger vanes or flaps are worked by vacuum; GM bulletin PI1260 for the 2014 Cruze 2.0 L diesel, for example, shows the pump filling a tank built into the EGR cooler, which in turn feeds the turbo and EGR control solenoids. The driver stage logs it on an open circuit or on a fault it cannot assign to low or high. No manufacturer documents P257A publicly; CARB 13 CCR 1968.2 treats such outputs as comprehensive components to be checked for circuit faults. P257B and P257C cover shorts to ground and to voltage.
P257A at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P257A
- Engine warning lamp on
- Vacuum-driven actuators such as EGR or turbo vanes respond poorly
Common causes of P257A
- Most likelyLoose or corroded connector at the reservoir control valve
- PossibleBroken wire in the control or supply line
- PossibleOpen solenoid coil in the control valve
- Less likelyFaulty output stage in the engine control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Vacuum reservoir control valveWiring harness
What each part of P257A means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| 7A | The exact fault in that area. |
What to do next
- Note P257A and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P257A
What does P257A mean?
P257A means "Vacuum Reservoir Control Circuit/Open". P257A is an output fault on the control line of the vacuum reservoir, usually a solenoid or switching valve the engine computer uses to connect, isolate or vent a vacuum storage tank. It is a generic code, so it means the same on every make.
Is it safe to drive with P257A?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P257A fail an emissions test?
Yes, it can. P257A is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P257A to fix?
Difficulty: medium. A typical repair takes 0.3 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P257A clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.