If you own a Porsche Cayenne from the 955 generation (model years 2003 through 2010), you may have come across the part number 955-628-320-04. This is the front lower control arm, a critical component of the vehicle's front suspension. Understanding what this part does, when it needs replacement, and how to choose the right one will keep your Cayenne handling safely and smoothly.
What Is Porsche Part 955-628-320-04?
The part number 955-628-320-04 refers to the front lower control arm (also called a front lower wishbone) for the left-hand side of the vehicle. It connects the wheel hub to the vehicle's subframe, allowing the wheel to move up and down while maintaining proper alignment. Made from forged aluminum, this control arm includes integrated ball joints and bushings.
Where Is It Located?
On a 955 Cayenne, the front lower control arm sits between the steering knuckle and the front subframe. There are two per front axle: one left (part 955-628-320-04) and one right (part 955-628-321-04). The left arm is what we are focusing on here.
Why Does It Fail?
Over time, the rubber bushings and ball joint wear out due to road stress, heat, and contamination. Typical lifespan is around 60,000 to 80,000 miles, but harsh driving or poor road conditions can shorten that. When the control arm fails, you'll notice symptoms like:
- Clunking or knocking sounds from the front suspension, especially over bumps.
- Loose or wandering steering.
- Uneven tire wear.
- Vibration in the steering wheel.
- Poor alignment that won't stay true.
Signs You Need to Replace Part 955-628-320-04
If you experience any of the above symptoms, inspect the front lower control arm. At home, you can jack up the front, support safely, and try to move the wheel side to side. Excessive play in the ball joint or cracked/deteriorated bushings indicate replacement is needed. A professional mechanic can also check during routine service.
Safety Implications
Driving with a worn control arm compromises handling and braking, and can lead to sudden failure, especially in emergency maneuvers. Replacement is not optional—it's necessary for safety.
Choosing a Replacement: OEM vs. Aftermarket
When buying part 955-628-320-04, you have two main options:
OEM Porsche Part
- Pros: Exact fit, known quality, integrated sensors (if your Cayenne has ride height sensors), and a warranty.
- Cons: Higher cost, often around $250–$400 per arm.
- Best for: Those who want guaranteed compatibility and are willing to pay a premium.
Aftermarket Options
- Pros: Lower price, typically $80–$200. Some brands offer improved bushings (polyurethane) for longer life.
- Cons: Fitment may vary, build quality can be inconsistent, and some aftermarket arms lack the necessary provisions for ride height sensors.
- Best for: Budget-conscious owners who do thorough research and select reputable manufacturers.
Important: If your Cayenne has air suspension with ride height sensors (common on many trims), the control arm must have a mounting tab for the sensor link. OEM and some high-quality aftermarket arms include it; cheap ones often omit it, causing a check engine light or suspension fault.
How to Replace the Front Lower Control Arm
Replacing part 955-628-320-04 is a job many DIYers can handle with moderate mechanical skill. Here's a general overview:
- Safety first: Lift the vehicle and support on jack stands. Remove the wheel.
- Disconnect: Remove the sway bar link, brake line bracket, and wheel speed sensor if needed.
- Unbolt: Remove the bolt securing the control arm to the subframe and the ball joint pinch bolt at the knuckle.
- Separate: Use a ball joint separator to free the arm.
- Install new arm: Position the new arm, apply anti-seize to bolts, and torque to spec.
- Reassemble: Reattach all components, then tighten the arm-to-subframe bushing bolt only after the vehicle is on the ground (with weight on suspension) to prevent pre-loading the bushing.
- Alignment: A professional four-wheel alignment is mandatory after replacement.
Tools Needed
- Metric sockets (18mm, 16mm, etc.), torque wrench, ball joint separator, jack stands.
- If your Cayenne has the ride height sensor, you'll need a thin wrench to avoid damaging the bracket.
Cost Considerations
Expect to pay:
- Part only: $80–$400
- Labor if you hire a shop: $200–$400 per side
- Alignment: $100–$150
Total for one side: roughly $350–$850. Replacing both sides is recommended because the other arm often fails soon after.
Final Recommendation
For most Cayenne owners, we recommend purchasing the OEM Porsche part 955-628-320-04 if you want hassle-free installation and long-term reliability. The extra cost is justified by the precise fitment and inclusion of the ride height sensor bracket. However, if your budget is tight and you have the time to research, a high-quality aftermarket arm from a trusted brand like Meyle, TRW, or Lemförder can work well—just confirm it has the sensor mount and read user feedback.
Always replace both lower control arms at the same time, and get a proper alignment afterward. This will restore your Cayenne's handling and extend tire life. If you're unsure, consult a Porsche specialist mechanic.