Porsche 957 Cayenne Xenon Headlight Ballast Control Unit 955.631.194.02 - Used Original Parts

Quick Answer

A Cayenne 957 headlight that flickers, cuts out once warm, or will not light at all, while the bulb and fuse test fine, usually points to a failed ballast. A tested Genuine used ballast is a sensible fix in Malaysia because the new part is expensive and the original unit is built to the same standard as the one that ran for years in our heat and humidity. It restores the factory xenon behaviour without paying for a new control unit.

Diagnosis and Common Symptoms

The ballast (xenon control unit) fires the D1S bulb with a high-voltage ignition pulse, then regulates it at a steady running voltage. Heat cycling, moisture inside the headlamp housing and age break down its internal electronics. On the Cayenne 957 the failure usually shows up in these ways:

• One headlight does not light at all, while the other side works normally.
• The light flickers, pulses, or shuts off after 5 to 20 minutes once the unit is hot.
• The light cuts out over bumps or when the car is started, then comes back later.
• A low beam or xenon warning appears in the instrument cluster or PCM, and the fault memory may hold a headlight or bulb circuit entry for that side.
• A faint clicking or repeated re-strike attempt is heard at the headlamp when the lights are switched on.

How to separate ballast from bulb:

• Swap the bulb from the working side to the faulty side. If the fault stays on the same side, the ballast or its wiring is the cause. If it follows the bulb, replace the bulb.
• If the bulb has gone pink or purple, the bulb is ageing and should be replaced, but this does not point to the ballast.
• Check the headlamp fuse and the 12V supply and ground at the ballast connector before condemning the unit.
• Inspect the housing for condensation or water marks. Moisture ingress kills ballasts repeatedly if the seal is not fixed.

Warning: the ignition pulse is dangerous. Switch the lights off, disconnect the battery and wait a few minutes before touching the ballast or bulb connector.

Introduction

This is a Genuine used Porsche xenon headlight ballast control unit, removed from a Cayenne 957 and bench and function tested before listing. We sell it as Genuine used, not as a copy, so the electronics, connector and housing match what Porsche fitted at the factory. Every unit is checked for stable ignition and steady output, so you are not buying a second fault. It suits owners who want a reliable, factory-grade repair at a fair cost.

Product Details

• Brand: Porsche
• Model Compatibility: Porsche Cayenne 957 (9PA) fitted with xenon / bi-xenon headlights
• Part Name: Xenon Headlight Ballast Control Unit (Part No. 955.631.194.02)
• Condition: Genuine Used (Tested Working)
• Notes: Match the part number on the label of your old ballast before ordering. Check the D1S bulb, the fuse and the connector for heat damage or corrosion when you fit it. Fix any moisture in the headlamp housing, or the new ballast will fail the same way. The ballast itself is normally plug and play. If the headlight or its leveling is also replaced, check headlight range setup afterwards.