Restricted Performance: Inlet Manifold – 3.0 V6 Diesel Engine

Models Affected:

The dreaded ‘Restricted Performance’ message on the dashboard can be caused by a multitude of issues on the 3.0 diesel engine. If however you can drive the car normally and the warning light only illuminates when you put the engine under load (for example, accelerating hard or going up a big hill) then there’s a good chance that you have a cracked inlet manifold.

This guide explains what can cause the inlet manifold to crack, the diagnostic fault codes typically logged in the ECU, and how to confirm and resolve the issue through inspection and removal of the failed unit and replacement with a new OEM part.

Symptoms

  • Loss of power and ‘Restricted Performance’ light on dash – car in limp mode.

  • This loss of power can happen when engine is put under load, hard acceleration or when driving up hills.

  • Engine enters limp mode under load

  • DTC Fault code: P006A-00 which indicates mass airflow sensor fault

  • DTC Fault code: P1247 – indicating low turbocharger boost pressure.

  • DTC Fault code: P2279 – indicating a leak in the air intake system.

Diagnosis & Cause

When scanned with diagnostics, most vehicles affected will log a P1247 fault code, which indicates low turbocharger boost pressure, or a P006A-00 DTC code, which indicates mass airflow issues. We also see P2279 when dealing with cracked inlet manifolds, and this points to an air intake leak.

If these errors are showing, then the inlet manifolds will need to be inspected, they have sponge covers over them, and if you look underneath and see oil residue then that is the tell-tale sign that there is a crack in the manifold and it needs to be replaced. If the vehicle has only gone into restricted performance a couple of times then there may not be any tell-tale oily residue build up yet, and the best way to confirm a cracked manifold is to perform a high pressure smoke test.

K Motors always recommend a high pressure smoke test is used to diagnose a cracked inlet manifold on the 3.0 Tdv6/Sdv6 engines as it is an 8 hour job to replace just one side. Please note, this will also help to rule out a blown inlet manifold/cam cover seal which would present with very similar symptoms.

How is the problem solved

The inlet manifolds are located atop either side of the V underneath much of the fuel system. Because of this removal involves disconnecting many fuel system components.

  1. Remove battery tray
  2. Fully drain cooling system
  3. Remove timing cover
  4. Perform a thorough inspection of the timing belt whilst it is visible (replacement would only take a few minutes at this point if required)
  5. Fully clean the manifold and oily contamination around it.
  6. Remove all fuel lines
  7. Disconnect fuel injectors
  8. Remove the 13 bolts holding the affected inlet manifold in.
  9. Replace inlet manifold with new gasket ensuring the 13 bolts are torqued in sequence and reverse above procedure.

Upon reinstallation, new seals are required for the fuel injectors to ensure there are no leaks in the high pressure fuel system.

Estimated Repair Costs

This estimate is inclusive of Removal of one faulty inlet manifold and replacement with a new OEM unit. Please note additional labour costs may be required if diagnostics including smoke test are required to verify the fault beforehand.

Frequently Asked Questions

The left hand inlet manifold cross references to the following part numbers:

LR019606, LR029145, LR055000, LR057379, LR073585, LR097158, LR105956, LR166213. LR179200

The right hand inlet manifold cross references to the following part numbers:

LR097157, LR116732, LR105957, LR179201, LR032818

We do not recommend you drive your car in Restricted Performance mode. The inlet manifold is not the only component that can cause this issue, something else may be at fault that cannot be identified without diagnostics.

Restricted performance also means that your vehicle will be in “limp-home mode” and performance will be very limited. This can be dangerous as you can lose power at a time when you really need it.

If it is a cracked inlet manifold, the engine will also be sucking soot through the intake system and potentially damaging various sensors and other sensitive components as well.

Just because one Inlet Manifold has gone it doesn’t necessarily mean that the other one will fail too. As they are either side of the engine, they are two separate jobs more or less so there’s no great saving in labour in getting them both replaced at the same time.

Yes, Restricted Performance under load could also be the throttle body on these 3.0 diesel engines, this is more likely if you also have a DPF full warning accompanying the Restricted Performance warning.

A failed gasket on the inlet manifold itself (commonly referred to as the cam cover, or rocker cover) would also produce many of the same issues and would require the same disassembly work, there would just be more oily residue sprayed up the engine.

Need help fixing this issue?

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