PT306 Engine

PT306 (P400) Ingenium Engine – Experiences, Issues, Fuel Consumption and Maintenance

Introduction: Successor to the legendary V6 engines

The engine with the code PT306, better known under the commercial name P400, represents a turning point for the Jaguar Land Rover (JLR) group. It belongs to the Ingenium engine family and was designed to replace the older, thirstier 3.0 V6 Supercharged engine.

This is an inline six-cylinder petrol engine (Inline-6) installed in heavy luxury cruisers such as the Range Rover IV (L405 facelift). Its key feature is the “Mild Hybrid” (MHEV) technology that uses a 48-volt system not only to save fuel, but also to power an electric supercharger that eliminates turbo lag before the main turbocharger spools up. This is an engine for drivers who want silky-smooth operation and brutal power.

Technical specifications

Reliability and Maintenance

Timing belt or chain?

The PT306 engine uses a timing chain. As with most Ingenium engines, the chain is located at the rear of the engine (towards the gearbox). Although JLR improved the chain design compared to earlier 2.0 diesel versions that had catastrophic issues, the chain’s position means that any intervention on it is extremely expensive because it requires removal of the engine or gearbox. So far, on the 3.0 petrol versions the chains do not show a tendency for early failure, but their condition should be monitored after 150,000 km.

Most common failures

Given that this is a relatively new and very complex unit, failures are often related to electronics and peripheral systems:

• Coolant leaks: Plastic thermostat housings and coolant pipes are prone to cracking due to high under-bonnet temperatures. Loss of coolant on such an engine can quickly lead to overheating of the aluminium block.
• 48V system issues: The MHEV system has its own lithium-ion battery and a DC-DC converter. There have been cases where a fault in the 48V system prevents the vehicle from starting.
• Software issues: Occasional warning lights on the instrument cluster related to emission control or hybrid system operation are often resolved by a software update at an authorised dealer.

Service intervals and oil

A minor service is recommended every 15,000 km or once a year, even though the manufacturer may state longer intervals (up to 26,000 km), which I, as a technical editor, do not recommend for such a highly stressed turbocharged engine.

Oil capacity: This engine takes a large quantity of oil, approximately 8.8 litres (depends on the exact VIN, but Ingenium six-cylinders have large sumps).

Oil grade: You must use 0W-20 with specific JLR approval (e.g. STJLR.51.5122). Using the wrong oil can damage the delicate variable valve timing mechanism and the turbocharger.

Oil consumption

Like any modern high-performance engine running thin 0W-20 oil, moderate oil consumption is possible. Consumption of up to 0.5 litres per 3,000–5,000 km can be considered acceptable, especially with aggressive driving. If the engine uses a litre per 1,000 km, this indicates a problem with the piston rings or the PCV valve (oil vapour separator).

Spark plugs

On engines with direct injection and turbocharging, spark plugs are under heavy stress. It is recommended to replace them every 60,000 to 80,000 km. Worn spark plugs can overload the ignition coils and cause misfires.

Specific Parts (Costs)

Fuel injection system

The engine uses advanced high-pressure direct injection (GDI) with pressures up to 200 bar. Injectors are generally reliable but sensitive to poor fuel quality. Symptoms of problems include rough idle and increased fuel consumption. The price of a single injector is high (very expensive, depending on the market).

Turbocharger and Electric supercharger

This is the most complex part. The engine has one twin-scroll turbocharger (driven by exhaust gases) and one electric supercharger (powered by the 48V system).

• Electric supercharger: It spins up to 120,000 rpm in 0.5 seconds to provide torque at low revs. Replacement is extremely expensive because it is integrated with complex electronics.
• Service life: With regular oil changes and proper turbo cool-down after fast driving, the turbocharger can last over 200,000 km. The electric supercharger is designed to last the life of the vehicle, but the technology is still too new for long-term predictions.

GPF filter and EGR

Yes, this engine is equipped with a GPF (Gasoline Particulate Filter) to meet strict Euro emission standards. Unlike diesel DPFs, GPFs rarely clog because petrol engines run at higher exhaust gas temperatures, which facilitates passive regeneration. An EGR valve is fitted for exhaust gas recirculation; it is prone to fouling, but less so than on diesels.

Fuel Consumption and Performance

City driving

Do not be misled by the “Mild Hybrid” badge. The Range Rover is a heavy vehicle (over 2.2 tonnes). In real-world city driving, fuel consumption ranges from 13 to 17 litres per 100 km. The start-stop system operates very smoothly thanks to the 48V system, but weight is still weight.

Is the engine “lazy”?

Absolutely not. With 400 hp and, more importantly, 550 Nm available from just 2000 rpm, this engine moves the Range Rover’s body with ease. Thanks to the electric supercharger, throttle response is instant – there is no waiting for the turbo to spool up. Acceleration is linear and convincing.

Motorway

This is the engine’s natural habitat. At 130 km/h, the gearbox keeps the engine at low revs (below 2,000 rpm in 8th gear), and fuel consumption drops to a more acceptable 9 to 11 litres per 100 km. Sound insulation and the smooth operation of the inline-six make the drive almost silent.

Additional Options and Modifications

LPG conversion (TNG/LPG)

Not recommended. The engine has direct fuel injection into the cylinders. Installing LPG requires a sophisticated “liquid LPG” system or a system that also injects petrol to cool the injectors. The cost of such a setup is very high (over EUR 1,500), and the risk of valve overheating and issues with the complex engine electronics is significant. The savings are hard to justify on a vehicle like this.

Chip tuning (Stage 1)

The engine is potent and has reserves. A Stage 1 remap can raise power to around 440–450 hp and torque to over 600 Nm. However, care must be taken due to thermal load. The cooling system is already complex, and additional heat can shorten the life of plastic components. It is recommended only from reputable tuners who understand JLR software.

Gearbox

Type of gearbox

With the PT306 engine in the Range Rover you get exclusively a ZF 8HP automatic gearbox (8HP76 variant). This is one of the best automatic transmissions in the world. A manual gearbox is not available on these models.

Gearbox reliability and failures

The ZF 8-speed is extremely reliable.

• Most common issues: Oil leaks from the gearbox sump (which is plastic) or from the mechatronic connector. Sometimes there are slight jerks when shifting from 1st to 2nd gear while cold, which is often resolved by a software update (adaptation).
• Dual-mass flywheel: Automatic gearboxes of this type do not have a classic dual-mass flywheel like manuals, but use a hydraulic torque converter. It is very durable, but if it fails (symptoms: vibrations at constant speed, slipping), overhaul is expensive.

Gearbox service

Although JLR often states that the gearbox oil is “fill for life”, the gearbox manufacturer (ZF) recommends changing the oil and filter (sump) every 80,000 to 100,000 km. This is crucial for gearbox longevity. The service kit (oil + sump with filter) is moderately priced (depending on the market), but it is a necessary expense.

Buying Used and Conclusion

When buying a Range Rover with this engine, make sure to check:

1. Cold start: Listen for any rattling from the rear of the engine (timing chain area) during the first 3–5 seconds of operation.
2. Cooling system: Check the coolant level and look for traces of leaks (white residue) around the engine. A sweet smell from the engine bay is a bad sign.
3. 48V system: Check whether the start-stop system works smoothly. If the engine cranks for a long time or battery warning lights appear, an expensive MHEV system fault is possible.
4. Service history: Due to its sensitivity to oil quality, proof of regular servicing is crucial.

Conclusion

The PT306 (P400) engine is an engineering gem that offers the best of both worlds – the smoothness of a petrol engine and torque that rivals diesels. It is ideal for buyers who want luxury and quietness and cover a moderate annual mileage. It is not cheap to maintain, but it is significantly more modern and refined than the old V6 units. If you can afford proper maintenance and quality fuel, this engine will put a smile on your face every time you press the accelerator.