🚗 Classic Fault — Mercedes-Benz W201 (1982–1993)
W201 190E idle speed hunting — auxiliary air valve
💰 Estimated Repair Cost
$25 – $80 GBP
Parts and labour estimate
🔧 Tools Required
Carb cleaner, multimeter
📋 Overview
The auxiliary air valve on the 190E K-Jetronic system fails and causes persistent idle speed fluctuation.
🩺 Symptoms
- Idle surges between 600-1400rpm
- engine stalls at junctions
- improves with valve disconnected
🔍 Possible Causes
- Failed auxiliary air valve
- dirty throttle body bypass
- air leak at intake
🛠️ Diagnosis Steps
Disconnect auxiliary air valve — if idle stabilises valve is failed. Clean throttle body bypass port.
✅ Most Confirmed Fix
Auxiliary air valve replacement
87% of users confirm this fix worked (28 reports)
🔗 Other Mercedes-Benz W201 Faults
Own a Mercedes-Benz W201?
Share your experience with this fault — or report a different issue. Your knowledge helps other classic car owners worldwide.