Piston Cooling Oil Jet Solenoid Failure | 2.0D Ingenium (Jaguar Models)

Models Affected:

The 2.0 Ingenium diesel engine uses an electronically controlled solenoid to manage oil flow to the piston cooling jets. These jets help keep piston temperatures under control when the engine is under load, reducing stresses and wear on the internals.

However, a common issue on the Ingenium is the failure of the piston cooling oil jet solenoid, usually triggered by coolant leaking from the thermostat housing onto the solenoid body and electrical connector.

This guide covers the symptoms, cause, and correct repair procedure for the piston oil cooling solenoid on Ingenium Jaguar models.

Symptoms of Piston Oil Cooling Jet Solenoid Failure (Ingenium Diesel)

  • Yellow engine management light (EML) on dashboard

  • Critically Low Oil warning message (even when oil level is correct)

  • Diagnostic Trouble Code (DTC): P25A9-00 Piston Cooling Oil Jet Solenoid Control

 

PLEASE NOTE: Do not top up the oil unless the level is actually low. This warning is often falsely triggered by the faulty solenoid unit, and is not related to the engine oil level.

Diagnosis & Cause

Much like on the Land Rover/Range Rover counterparts, The most common cause of piston oil cooling jet solenoid failure on the 2.0 Ingenium diesel fitted to Jags is a leak from the thermostat housing gasket, which allows coolant to drip directly onto the piston cooling solenoid. Over time, this damages the solenoid and/or its connector, resulting in a P25A9-00 fault code, the “Critically Low Oil” warning message and the engine management light illuminating.

This issue doesn’t tend to put the car into limp mode, but it does need to be addressed quickly to avoid false oil level warnings and potential long-term engine damage.

How is the problem solved

Access is best achieved from the top of the engine. The job requires removal of several components to reach the solenoid and thermostat. This procedure remains mostly the same on models with transverse and longitudinal 2.0 Ingenium engines.

Step-by-step summary:

  1. Remove engine cover
  2. Drain coolant
  3. Remove fuel filter and housing
  4. Disconnect plastic fuel pipes
  5. Remove glow plugs
  6. Disconnect intercooler boost hose
  7. Undo 10x manifold bolts and remove the inlet manifold
  8. Remove thermostat
  9. Remove 8mm bolt and carefully prise out the piston cooling solenoid, ensuring the electrical connector for the unit is also disconnected
  10. Fit new solenoid and thermostat gasket
  11. Reassemble all components in reverse order
  12. Refill coolant, clear diagnostic faults, and test drive the vehicle to confirm resolution

The following parts will need to be replaced:

  • AJ813393 – Piston Cooling Solenoid Valve
  • JDE39873 – Thermostat Seal / Gasket

Estimated Repair Costs

This estimate includes the replacement of the piston cooling solenoid, thermostat gasket, fresh coolant, and labour on the 2.0 Ingenium diesel engine fitted to a Jaguar E-Pace. VAT is also included.

Please contact us with your registration for a personalised estimate based on the engine layout of your vehicle.

For Ingenium Land Rover Models please see our page here.

Frequently Asked Questions

You can, but we do not recommend it. While the engine likely won’t enter limp mode with a faulty piston oil cooling jet solenoid, the “Critically Low Oil” message may continue appearing, making it difficult to know if a genuine oil issue occurs.

In the medium to long term, the pistons may also receive insufficient oil cooling, leading to increased wear on the internals.

The Ingenium diesel engine is well known for its share of oil delivery and engine issues including turbocharger and timing chain failure, and this could be exacerbated by further wear of the bottom end and components running too hot.

No, the failure is electrical and sensor based. It does not immediately affect oil pressure or engine cooling, but the unit may not function correctly leading to insufficient oil cooling.

Topping up the engine oil will only help if the oil level is genuinely low. This fault is known to raise false oil level warnings, so always check the dipstick before adding oil.

Overfilling can cause its own issues including oil seal failure.

In most cases, no. If coolant has leaked onto or into the unit, the solenoid internals and/or the connector are likely to be damaged. Replacement is the only reliable solution.

Need help fixing this issue?

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