Checking control valve for leaks — AUDI
Checking control valve for leaks on Audi: 15 steps. What to remove, in what order, and what to check after.
On cars on the 4A platform code with hydraulic self-levelling, a sagging rear end overnight often comes down to the control valve, and this test proves it with a pressure gauge and time. The self-levelling tester is first bled through the connector's bleed screw, then plumbed into the pressure pipe at the left or right pressure container. The luggage compartment is loaded with about 100 kg, the engine is idled until the gauge reaches roughly 50 bar, and the ignition goes off. The car then stands for around 3 hours. A drop of more than 5 bar means the control valve is leaking and should be replaced. Getting a clean starting reading, with the tester properly bled, decides whether the comparison means anything.
🧭 Before you start
Bleed the self-levelling tester via the bleed screw on the connector, then connect it to the pressure pipe at one pressure container. Load about 100 kg into the boot, idle the engine and switch off at approximately 50 bar, noting the reading. After roughly 3 hours check the drop: more than 5 bar condemns the control valve. Remove the tester and top up the hydraulic reservoir.
Fits: platform code 4A
- Opens: power steering fluid
Don't miss
- Bleed the tester hose through the bleed screw before connecting it, catching fluid in a vessel.
- Load the luggage compartment with approximately 100 kg before building pressure.
- Switch off at around 50 bar and write the reading down.
- Allowed drop after roughly 3 hours is 5 bar; more means a leaking control valve.
- Check and top up the hydraulic fluid in the reservoir once the tester is off.
Written for this job from the workshop steps below · TorqFix editorial.
📋 Procedure
- Detach the dust cap from the bleed screw.
- Attach the bleed hose of the self-levelling suspension system testerV.A.G 1354 to the bleed screw.
- Open the bleed screw and collect the hydraulic fluid emerging with a suitable vessel.
- Close the bleed screw at the connector.
- Detach the bleed hose from the bleed screw of the connector and attach to the bleed screw of the pressure tester.
- Unscrew the pressure pipe at the left or right pressure container.
- Connect the self-levelling suspension system testerV.A.G 1354 to the pressure pipe.
- Load the luggage compartment with approx. 100 kg.
- Start the engine and let it idle.
- Observe the reading on the pressure gauge and switch off the ignition at approx. 50 bar. Note down the gauge pressure.
- Leave the vehicle for roughly 3 hours.
- Check the reading on the pressure gauge: Max. pressure drop 5 bar.
- If the drop in pressure is more than 5 bar, the control valve is leaking and should be replaced.
- Remove the self-levelling suspension system testerV.A.G 1354.
- Check the hydraulic fluid level in the reservoir and replenish the fluid if necessary.
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Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
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The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.