2017 Land Rover Discovery Auxiliary Coolant Pump: Fixing Pre-Heater Problems
This small electric pump is essential for your Land Rover's pre-heating system, and its failure is a common cause of no-heat issues in cold weather.
- This part is NOT the main water pump; it is an auxiliary pump for the fuel-fired pre-heater system.
- Failure will NOT cause the engine to overheat but will result in poor or no cabin heat, especially at idle or when using the park-heat feature.
- The most common failure symptoms are a lack of heat, a buzzing noise from the pump, and fault code P2600.
- Before purchasing, verify your vehicle has the fuel-fired pre-heater option by looking for a small exhaust pipe in the front passenger wheel well.
Symptoms of a Failing Auxiliary Coolant Pump
A problem with the auxiliary coolant pump for the pre-heater will not cause the engine to overheat, but it will create noticeable issues with comfort and convenience features, especially in cold weather. Watch for these specific signs.
- No Heat from Pre-Heater: The most obvious symptom is when the remote or timed park-heat function runs, but the vehicle interior remains cold. The fuel-burning heater might ignite, but without the pump circulating coolant, the heat never reaches the cabin.
- Inconsistent Cabin Heat at Idle: You may notice that the heater blows warm air while driving at speed, but the air turns cool or lukewarm when you are stopped at a traffic light or idling. This happens because the main engine water pump isn't spinning fast enough at idle to circulate sufficient coolant, a job the auxiliary pump is supposed to take over.
- Buzzing or Whining Noise: A high-pitched buzzing or whining sound coming from the engine bay, which may continue for a short time after the engine is turned off, can indicate an electrical problem or failing bearings inside the pump.
- Fuel-Burning Heater (FBH) Won't Stay On: The pre-heater system has safety sensors. If it detects that coolant is not circulating (because the pump has failed), it will shut down to prevent itself from overheating. After several failed attempts, the system may enter a "lockout" mode and will not try to start again until it is reset.
- Diagnostic Trouble Codes (DTCs): A failed pump can trigger a specific fault code. The most common is P2600 - Coolant Pump "A" Control Circuit/Open, which indicates the engine's computer cannot communicate with the pump.
Pro Tip: Before blaming the pump, check the pre-heater system's fuse. On some Land Rover models, pulling the correct fuse for a few seconds can reset a system lockout caused by multiple failed start attempts.
Buying a Used Coolant Control Valve
A used OEM auxiliary pump can be a reliable and cost-effective alternative to an expensive new part. Since this is not a primary cooling system component, the risks are lower, but a careful inspection is still essential.
What to Inspect Before You Buy:
- Check for Leaks: Carefully examine the seams of the plastic housing. Look for any white, pink, or orange crusty residue, which indicates a past coolant leak. A TSB for the main water pump notes that some dry residue can be normal, but any sign of a fresh or significant leak is a red flag.
- Inspect the Electrical Connector: The connector should be clean and free of corrosion. The pins inside should be straight and unbroken. A damaged connector can prevent the pump from receiving power.
- Examine the Plastic Housing: Look for any cracks, deep scratches, or signs of melting. The pump is located in the engine bay and is exposed to high temperatures, so any physical damage could lead to premature failure.
- Verify Part Numbers: Match the OEM part number on the used part to your original. The most common part numbers for this application are GPLA-8B500-AB, LR039070, and LR116465. Using the correct part number ensures compatibility with your vehicle's control module.
Choosing a used OEM part over a cheap aftermarket alternative is often a wise decision. OEM parts are built to Land Rover's exact specifications for flow rate and electrical resistance, ensuring they work correctly with the vehicle's complex electronic systems. An incompatible aftermarket pump may not run at the correct speed or could cause fault codes.
Known Issues, Recalls, and TSBs
For the 2017 Land Rover Discovery, there are no official recalls or Technical Service Bulletins (TSBs) directly related to the auxiliary coolant pump for the fuel-fired heater. However, it's helpful to be aware of related information:
- Recalls: The 2017 Discovery has active recalls for rear door latches, trailer light functionality, and a fuel gauge software error. None of these affect the cooling system.
- Heater Core Blockage: On some Land Rover models, the heater core itself can become partially clogged. This can cause symptoms similar to a failing auxiliary pump, such as uneven heating between the driver and passenger sides. If replacing the pump doesn't solve your heating issues, a heater core flush may be necessary.
Cost Comparison
The cost to replace the auxiliary coolant pump can vary significantly depending on the type of part you choose and whether you perform the labor yourself.
| Part Type | Estimated Cost |
|---|---|
| New OEM (Dealer) | $240 - $300 |
| New Aftermarket (OEM Supplier like Pierburg) | $140 - $180 |
| Used OEM | $50 - $100 |
| Shop Labor | $250 - $600 |
Replacement Overview
- Difficulty: 2 out of 5 (Easy to Moderate)
- DIY Feasible: Yes, for those comfortable with cooling system work.
- Estimated Time: 1-2 hours.
Replacing this pump is generally straightforward. It involves partially draining the coolant, accessing the pump in the engine bay, clamping off the attached hoses to minimize coolant loss, disconnecting the two hoses and the electrical connector, and swapping the unit. The system will then need to be refilled with the correct spec coolant and bled of any air pockets.
Frequently Asked Questions (FAQ)
Is this auxiliary pump the same as the main water pump?
No. This is a small, electric pump specifically for the pre-heating and auxiliary heating circuit. The main engine water pump is a much larger, belt-driven component responsible for the engine's primary cooling. A failure of this auxiliary pump will not cause your engine to overheat while driving.
What happens if I don't replace a failed auxiliary coolant pump?
The vehicle will remain safe to drive. However, the fuel-fired pre-heater will not function, and you may experience poor or inconsistent cabin heat, especially when the engine is idling in cold weather. The main cooling system will not be affected.
How do I know if my Land Rover has a fuel-fired pre-heater?
The easiest way to check is to look for a small, dinky exhaust pipe in the front passenger-side wheel well area. This is the exhaust for the heater unit. This feature is common on diesel models and vehicles originally sold in colder North American regions.
Can a bad auxiliary pump drain my battery?
Yes. If the pump fails due to an internal electrical short, it can sometimes continue to run even after the vehicle is turned off, creating a parasitic battery drain. This is often accompanied by a continuous high-pitched buzzing sound from the pump.
Technical Specifications
OEM Part Numbers: GPLA-8B500-AB GPLA8B500AB LR039070 LR116465
Voltage: 12V, Electrical Connector: 3-Pin
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Land Rover Discovery: