A failed temperature sensor integrated into the bypass valve B assembly or its signal circuit; A bypass valve B that is stuck closed or restricted, causing charge air to overheat; Damaged, chafed, or corroded wiring and connectors at the bypass valve B temperature sensor; A faulty powertrain control module driver circuit for the bypass valve B temperature input; Low coolant level or a cooling system fault that raises charge air temperature beyond normal limits; A restricted intercooler or charge air cooler that cannot shed heat before the bypass valve; Software calibration issues in the powertrain control module that misreport bypass valve temperature

DTC codes / P00xx · Fuel and air metering and auxiliary emission controls / P00D8

P00D8Turbocharger/Supercharger Bypass Valve B Temperature Too High

P00D8 means the powertrain control module has detected that the temperature signal from the turbocharger or supercharger bypass valve B is higher than the calibrated safe limit. The computer monitors a dedicated temperature sensor or a modeled value for that bypass valve circuit and sets this code when the reading exceeds the threshold for a set time.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering and auxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other symptoms besides the warning light
Reduced engine power or limp mode when the bypass valve is commanded to protect the turbocharger or supercharger
Rough idle or stumble after a cold start if the bypass valve is stuck partially open
Poor acceleration or delayed boost response because the bypass valve cannot regulate charge air temperature properly
A noticeable whistle or hissing sound from the turbocharger or supercharger area if the bypass valve is stuck or leaking
In rare cases, an overheating smell or heat-related damage to nearby wiring and hoses

Common causes, most likely first

A failed temperature sensor integrated into the bypass valve B assembly or its signal circuit
A bypass valve B that is stuck closed or restricted, causing charge air to overheat
Damaged, chafed, or corroded wiring and connectors at the bypass valve B temperature sensor
A faulty powertrain control module driver circuit for the bypass valve B temperature input
Low coolant level or a cooling system fault that raises charge air temperature beyond normal limits
A restricted intercooler or charge air cooler that cannot shed heat before the bypass valve
Software calibration issues in the powertrain control module that misreport bypass valve temperature

How to diagnose and fix it

Scan all modules for stored and pending codes, then record freeze-frame data for P00D8 to see the temperature value and engine conditions at the time of failure
Visually inspect the bypass valve B connector, pins, and harness for corrosion, chafing, or loose terminals, and repair any wiring faults before replacing parts
Use a scan tool to compare the bypass valve B temperature reading with a known-good value or an infrared thermometer at the valve body when the engine is cold and again after warm-up
Check the charge air cooling system, including coolant level, intercooler condition, and any related hoses, for restrictions or leaks that could raise bypass valve temperature
Test the bypass valve B actuator and temperature sensor circuit with a multimeter for resistance and voltage values against the manufacturer's specification
Replace the bypass valve B assembly or its temperature sensor only after electrical and cooling system checks confirm the sensor or valve is at fault
Clear the codes, perform a road test with live data monitoring, and verify that the bypass valve B temperature stays within the normal range and the code does not return

Before you replace the bypass valve B

A common misdiagnosis is replacing the bypass valve B assembly when the real problem is a chafed signal wire near the exhaust or turbocharger that shorts to ground only when hot.
P00D8 can be set by a cooling system fault that raises charge air temperature, so always verify coolant level and intercooler airflow before condemning the valve.
Some vehicles use a modeled bypass valve temperature rather than a physical sensor, meaning a faulty manifold absolute pressure sensor or intake air temperature sensor can skew the calculated value and set this code.
A stuck-closed bypass valve B can cause elevated charge air temperature without any obvious drivability symptom, so the warning light may be the only clue until the valve is inspected.
After repairs, the powertrain control module may need a relearn or adaptation reset for the bypass valve before the monitor will run and clear the code permanently.

Can I keep driving with P00D8?

You can usually drive the vehicle short distances at moderate speed to a repair shop, but avoid heavy throttle and sustained boost because a stuck bypass valve can overheat charge air and damage the turbocharger or supercharger. If the engine enters limp mode or you smell overheating, stop driving and have the vehicle towed.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.