What does it mean?
P1288 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Turbocharger Bypass Valve Short to B+ .
Symptoms
- MIL (check engine lamp) on
- Boost surging or fluttering, and an audible compressor chatter when lifting off the throttle
- Loss of boost and reduced power under acceleration
- Rough idle or a stall right after a quick throttle release
- Limp mode with the wastegate/bypass strategy disabled
Likely causes
- Control wire chafed against a battery feed inside a harness bundle
- Melted insulation where the harness runs close to the turbocharger or exhaust manifold
- Oil or water in the valve connector bridging the control pin to a supply pin
- Internally shorted bypass valve solenoid winding
- Damaged or mis-seated terminal in the connector allowing pin-to-pin contact
- Failed control module low-side driver, only after the wiring is proven good
How to fix it
- Read the freeze frame, then command the bypass valve open and closed with the scan tool and watch for a response
- Unplug the valve; if the fault changes to an open-circuit code, the short is inside the valve
- Measure solenoid resistance and compare it with specification
- With the valve unplugged and the key on, check whether battery voltage is present on the control wire
- Inspect the harness routing around the turbocharger and manifold for melted or hardened insulation
- Repair the damaged harness section, or replace the valve if its winding is shorted
- Clear the code and road test under boost while monitoring actual against desired boost