Exhaust gas recirculation valve EGR. Porsche 958 Cayenne S Diesel 4.2L

Exhaust gas recirculation valve EGR. 
The EGR valve is a recirculation control valve that regulates the flow of exhaust gases back into the intake on qualifying Porsche 958 4.2L diesel engines. It’s a critical emissions control and combustion-management component - controlling EGR flow to manage NOx emissions, combustion temperature, and overall engine efficiency. Fits left or right
Price is each, 2 required per car.

Fits:
Porsche 958 Cayenne S Diesel V8 4.2ltr 2010 - 2017

Diagram ref no 20

This EGR valve:

• Recirculates a controlled portion of exhaust gases into the intake to lower combustion temperature and reduce NOx emissions.
• Maintains proper valve flow and sealing to ensure consistent emissions control and engine performance.
• Provides reliable operation, with correct internal valve timing and robust valve sealing to prevent leaks or exhaust escape.
• Restores proper EGR function when the original valve fails, is stuck, or leaks - helping avoid emission faults, poor idling, or performance issues.

A failing EGR valve can cause poor combustion, increased emissions, and reduced engine efficiency, especially on diesel models that rely heavily on proper exhaust recirculation. As carbon builds up or the valve sticks, the engine may experience rough running, hesitation, smoke, or higher operating temperatures. Replacing a worn EGR valve restores correct exhaust-gas flow, maintains emission compliance, prevents exhaust leaks, and helps protect the engine from unnecessary stress or long-term damage.

Consider replacing the EGR valve if:
• There are error codes related to EGR failure or emissions fault.
• Engine shows rough idle, hesitation, or reduced performance under load.
• There’s excessive smoke or poor combustion performance, especially on a diesel engine.
• The original valve is faulty, leaking, stuck, or otherwise degraded due to age / carbon build-up.
• Performing an engine maintenance, overhaul, or emission-system service, especially if the EGR hasn’t been replaced before.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

958131501

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