Vehicles using B4204T26 engine list:

Engine B4204T26

Symptoms:
- Rough idling or engine misfire
- Loss of power or hesitation during acceleration
- Check Engine Light (CEL) illumination
- Excessive oil consumption or oil leaks
- Turbo lag or reduced turbocharger performance
- Unusual noises such as ticking or knocking from the engine

Diagnosis:
- Use an OBD-II scanner to check for fault codes related to ignition coils, fuel injectors, or turbocharger sensors.
- Inspect ignition coils and spark plugs for wear or damage, as misfires are common.
- Check for vacuum leaks or intake manifold issues causing rough idling.
- Examine turbocharger operation and boost pressure sensors for faults.
- Inspect for oil leaks around valve cover gaskets and turbocharger oil lines.
- Perform compression and leak-down tests to assess engine internal condition if knocking noises are present.

Fixes:
- Replace faulty ignition coils and worn spark plugs to resolve misfires and rough running.
- Repair or replace leaking valve cover gaskets and turbo oil feed/return lines to prevent oil loss.
- Clean or replace the turbocharger boost pressure sensor and ensure turbocharger is functioning correctly.
- Address vacuum leaks by replacing cracked hoses or faulty intake manifold gaskets.
- Update engine software if Volvo has released technical service bulletins addressing known issues.
- In severe cases of engine knocking, further mechanical repairs such as piston or bearing replacement may be necessary.

Prevention:
- Follow recommended oil change intervals using high-quality synthetic oil to protect turbocharger and engine internals.
- Use OEM or high-quality replacement parts for ignition and fuel system components.
- Regularly inspect and maintain the turbocharger system, including air filters and intercooler cleanliness.
- Avoid prolonged idling and aggressive driving to reduce stress on the turbocharger and engine.
- Schedule routine diagnostic checks to catch early signs of ignition or turbocharger issues before they worsen.