What's in the Kit

OEM Part Numbers & Cross-References

Technical Specifications

Product Description

This bundle combines two essential components for a complete 4th generation Haldex AWD service: the N373 solenoid control valve (part 0AY598554C) and the OEM seal kit (part 0AY598301). Together they address the two most frequent failure points of the Gen 4 Haldex coupling – solenoid valve failure causing AWD disengagement, and housing seal degradation causing oil contamination and pressure loss.

What the N373 Valve Does

• Controls the clutch operating angle and oil pressure in the Haldex coupling
• Regulates hydraulic pressure to engage and disengage the rear axle clutch pack
• Receives PWM signals from the Haldex ECU to modulate torque transfer
• When faulty: AWD disengages, fault code 02248 stored, front-wheel-drive only mode activated

What the Seal Kit Does

• Reseals the Haldex control unit housing after N373 valve replacement
• Prevents Haldex oil from contaminating the ECU/control unit electronics
• Restores correct pressure containment within the coupling housing
• Includes sealing strip, gasket and mounting screws – all required for a complete re-assembly

Why Bundle These Two Together?

• Single service job – replace the valve and reseal the housing in one session, avoiding a second disassembly
• Cost-effective – tested used N373 valve at a fraction of the new part price, combined with a new OEM seal kit
• Prevents future leaks – old seals harden and crack over time; always replace seals whenever the housing is opened
• OEM quality – both components are genuine BorgWarner parts, ensuring correct fit and long-term reliability

Vehicle Compatibility

This repair set fits all vehicles equipped with the 4th generation Haldex AWD coupling. Check the generation label on your Haldex unit or consult your vehicle handbook to confirm Gen 4 fitment before ordering.

Target Fault Codes – What This Kit Fixes

The following fault codes are typically caused by a failed N373 valve or leaking Haldex housing seal. Use a VAG-compatible diagnostic tool (VCDS, ODIS, ISTA or equivalent) to read the Haldex / AWD module.

Installation Guide

Preparation

• Drain Haldex Gen 4 oil from the coupling housing before opening
• Clean the exterior of the coupling housing to prevent contamination
• Have a VAG-compatible diagnostic tool ready for fault code clearing and Pump Learn calibration after installation

N373 Valve Replacement

• Disconnect the N373 valve electrical connector
• Remove the retaining bolt / clip and extract the old valve
• Inspect the valve bore for contamination or damage
• Insert the replacement N373 valve and secure with the retaining fastener
• Reconnect the electrical connector

Seal Kit Application (0AY598301)

• Remove the Haldex control unit from the housing (disconnect electrical connectors, remove mounting bolts)
• Clean the mating surfaces of the control unit and housing thoroughly
• Apply the new sealing strip (from 0AY598301 kit) to the housing groove
• Position the new gasket correctly and refit the control unit
• Secure with the new screws from the kit – tighten to correct torque

Post-Installation

• Refill with fresh Haldex Gen 4 oil (recommended at every service)
• Clear all stored fault codes using VCDS / ODIS or equivalent
• Perform Pump Learn / Basic Settings calibration with engine running
• Test drive to verify AWD engagement and confirm no fault codes return

Why Gen 4 Haldex N373 Valves Fail

1. Contaminated Haldex Oil

The N373 valve operates in the Haldex oil bath. When the oil is not serviced at the recommended intervals (every 30,000–40,000 km), metal particles and degraded oil clog the valve orifice, causing erratic pressure control or complete valve seizure.

2. Electrical Failure – Solenoid Coil

Internal short-circuit or open-circuit in the solenoid coil prevents the valve from receiving PWM signals. The ECU detects no valve response and stores fault code 02248. A simple resistance check of the valve coil reveals this failure.

3. Housing Seal Degradation

The rubber sealing strip and gasket (0AY598301) harden and crack with age and thermal cycling. This allows Haldex oil to leak into the control unit housing, damaging the PCB and causing multiple fault codes including communication failures and pressure sensor errors.

4. Wear & Age

After 150,000–200,000 km, the precision-machined valve body wears beyond tolerance, causing pressure regulation drift. The coupling fails to build sufficient pressure for full AWD engagement, resulting in intermittent 4WD operation.

Quality Assurance & Warranty

12-Month Warranty: The N373 solenoid valve is fully tested and covered by a 12-month functionality warranty. The 0AY598301 seal kit is a new OEM component.

Warranty Coverage Includes:

• N373 valve – solenoid coil and mechanical function
• Correct oil pressure regulation and PWM response

Warranty Exclusions: Damage caused by contaminated oil, incorrect installation, failure to perform Pump Learn calibration after installation, or use in non-compatible Haldex generations.

Shipping

Worldwide Shipping – We ship to most countries globally. If your country is not available at checkout, please contact us directly and we will process the order personally.

• Securely packaged to prevent damage in transit
• Tracking number provided for all shipments
• Express options available – contact us for details

Need Help or Have a Question?

Our technical team is available to assist with compatibility checks, installation guidance, and fault code diagnosis.

Important Purchase Information