Low Pressure EGR

• The LP EGR system is used on EU5 and EU6 market vehicles only.
• The LP system takes exhaust gases from the exit of the Diesel Particulate Filter (DPF) system, and mixes it with the fresh air intake into the turbocharger.
• The gases are transported from the DPF outlet to the LP EGR cooler via a pipe. The LP cooler has no bypass mode, so only cools.
• There is a simple mesh filter fitted before the gasses reach the outlet of the cooler that prevents larger particles of soot etc. from entering the turbo charger system. The mesh filter is a non-serviceable component.
• The cooled gases are then directed through the LP EGR valve, via a butterfly flap.
• The valve consists of a tube between the fresh air duct and the turbocharger, with the butterfly valve covering the EGR inlet, in the center bottom of the EGR valve.
• The butterfly valve opens into the fresh air stream, promoting both thorough mixing before the gas enters the turbocharger, and also provides 'suction' to drive the LP EGR gas through the system.

Possible Causes

• Excessive undetected soot in the DPF
• Charged air induction system leak
• Low pressure EGR cooler blocked / filter blocked
• Low pressure EGR valve mechanical integrity
• Low pressure EGR differential pressure sensor mechanical integrity
• Connector is disconnected, connector pin is backed out, connector pin corrosion
• Vehicle is fitted with TWO EGR valves a LP and HP unit. One is DPF side to turbo the other is exhaust manifold to intake manifold.

Repair Steps

1. Using a HP smoke detector visually inspect the air intake system for leaks. And repair any that are found.
2. If there are no signs of soot particles this is not the cause of the customers concern
3. Remove low pressure EGR cooler housing lid and visually inspect for soot particles.
4. Is the cooler blocked, See #NOTE# blocked LP EGR cooler filter image below. We have seen the filters internally block as per the image below, this would require a new filter set LR126126 cleaning of the EGR/Throttle body and the Low pressure EGR cooler.
5. Low pressure EGR pipe on the nearside is it blocked.
6. Look for signs of sooting around the clamp.
7. Black soot around the tail pipe.
8. Loosen the SCR assembly, look up into the cooler and check for excessive levels of soot.
9. DPF/SCR canister cracked internally.
10. JLR process change LP EGR and cooler.
11. Change cooler pressure sensor and SCR/DPF unit.
12. Pressure sensor is bolted to the intake side of the engine looks like a DPF pressure sensor one goes to the cooler pack and the longer pipe goes to cooling unit this measures the pressure either side of the unit.
13. If the cooler also shows signs of being excessively blocked, then the cooler may need replacing as well.
14. The DPF may also need inspecting for cracks that can draw in air from the outside causing excessive sooting.
15. After the repair, reconfigure existing PCM with latest software with a dealer tool.

• Check soot mass in the oil and if too high carry out an oil service, or;
• Oil dilution factor 0 Zero good, 10 bad if too high carry out an oil service.

Replacement Kit

Soot IS visible DPF NOT OK.

Visually check for any potential signs of cracking or leaks, Leaks can be evident from rusting water marks or even carbon build up at the exterior seams!

Picture details area of DPF filter internal collapse/failure.

Inside view showing the DPF internal collapse / brealk down.

Blurred outer edging shows output side of the DPF, clearly with soot present, which indicates a DPF problem.

Pictured DPF showing cracks is a sign of internal collapse and breaking down.