Restricted Performance - Throttle Body Failure (3.0Tdv6 & Sdv6)

At K Motors, we regularly diagnose “Restricted Performance” faults across a variety of Land Rover and Jaguar vehicles fitted with the 3.0 Tdv6 and Sdv6 engines. While this warning can be triggered by a variety of issues, one of the most common and overlooked causes is a sticking or soot-clogged throttle body. If left unresolved, it can also prevent the engine from completing a DPF regeneration cycle, eventually triggering a ‘DPF Full’ red warning and causing further issues down the line.

This guide explains what causes the throttle body to fail, the diagnostic fault codes typically logged in the ECU, and how to confirm and resolve the issue with a simple physical inspection and replacement.

When scanned with diagnostics, most vehicles affected will log a P0234 fault code, which indicates a turbo overboost condition. Often, this is a symptom rather than the root cause. The real issue on the 3.0 Diesel engine generally lies with the throttle body. When it becomes clogged up with carbon deposits, the valve inside sticks and fails to open/close correctly, cause intake airflow levels to run outside of expected parameters and triggering limp mode.

This also prevents the engine from carrying out a normal DPF regeneration, since the exhaust temperatures aren’t able to reach the necessary threshold. Over time, this results in the DPF becoming full and potentially completely blocking up, further reducing engine performance and potentially creating more expensive issues.

The throttle body can be physically checked by disconnecting the intake hose and visually inspecting the valve. If soot buildup is evident and the flap is restricted, a replacement throttle body is required.

It is a fairly simple repair to replace the throttle body, and specialist tools are not required to replace the unit itself;

1. Disconnect the electrical connectors – one on the front-left side of the body and one on the MAP sensor on top.
2. Loosen the two hose clamps securing the inlet and outlet pipes.
3. Remove the 10MM bolt through the centre of the throttle body.
4. Remove the C-clip and front cover to expose the mounting.
5. Carefully remove the throttle body by wiggling it free from the inlet manifolds.
6. Fit the new unit in reverse order.

Once fitted however, you will need diagnostic equipment to reset the fault codes and to perform a forced regeneration of the DPF unit if the DPF full message was showing. Provided that the DPF is not fully blocked, that should be it. If the DPF does not clear upon regeneration though, removal and manual cleaning of the unit may be required. Because of this, we recommend that you book in for diagnostics as soon as you experience the any of the above symptoms.

This estimate is inclusive of diagnostics, removal of the faulty throttle body unit and replacement with a new OEM unit. Please note additional labour costs may be required if a DPF regeneration to clear the particulate filter is needed.

Call us on 01772 368807 or get in touch online to book a repair or get friendly advice.