Fuel and air

P00D8 — Turbo/Supercharger Bypass Valve 'B' Temperature Too High

Severity: medium Drive with care, to a shop

What P00D8 means

The engine control unit detected a temperature at boost bypass valve 'B' that is higher than expected. This valve vents excess boost pressure or recirculates air to protect the turbocharger or supercharger. The cause can be real overheating, a faulty valve, or a bad temperature sensor signal or wiring problem.

Symptoms

  • Check Engine light on
  • Reduced power and poor acceleration
  • Limp mode with limited boost
  • Low or erratic boost pressure
  • Unusual turbo noise or whistling
  • Higher exhaust or under-hood temperatures

Possible causes

  1. Stuck or faulty bypass valve 'B'
  2. Failed temperature sensor or inaccurate signal
  3. Damaged or corroded wiring and connectors to the sensor or valve
  4. Restricted intercooler or airflow causing excess heat
  5. Turbo actuator or position sensor fault
  6. Sticking variable geometry mechanism
  7. Charge-air or vacuum leak

How to diagnose

  1. Scan all codes and freeze frame data and note the conditions when it set
  2. Inspect wiring and connectors at the temperature sensor and valve for heat damage, corrosion or chafing
  3. Check charge-air hoses, pipes and vacuum lines for cracks and leaks
  4. Compare specified and actual boost pressure in live data
  5. Check the temperature sensor reading cold and while warming up against other sensors
  6. Test actuator and valve movement through the full range for sticking
  7. Inspect the intercooler and intake path for restrictions or oil buildup
  8. Check power and ground at the valve and sensor connectors

Common fixes

  • Replace the faulty bypass valve 'B'
  • Repair or replace damaged wiring and connectors
  • Replace the failed temperature sensor
  • Clear intercooler or airflow restrictions
  • Replace or adjust the turbo actuator and position sensor
  • Fix boost and vacuum leaks

Questions and answers

What does P00D8 mean?

It means the ECU sees too high a temperature at boost bypass valve 'B'. The cause may be the valve, the sensor, the wiring or genuine overheating.

Can I drive with P00D8?

Briefly and gently, for example to a shop. Avoid heavy load, because real overheating can damage the turbo and engine.

How do I clear P00D8?

Clearing it with a scan tool only helps temporarily. Find the cause first by checking wiring, sensor, valve and the air path, or the code will return.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.