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BMW VANOS System Fault Testing and Diagnosing

The Definitive Guide and How to

In this technical article, we will give you the definitive guide on diagnosing BMW variable-valve timing (VANOS) faults. The procedure will take you through multiple checks, tests and visual inspections to determine what is causing the symptoms and fault codes on the BMW you are working on.

In this article, a BMW E90 will be used. Other BMW models are similar and the diagnosis can be used with slight variations. At any point in this procedure that you find an incorrect state or faulty component, repair the item, clear adaptations and recheck system for fault codes.

The following BMW models are often affected by these issues:

  • 2006-2010 BMW 325i 
  • 2006-2010 BMW 330i 
  • 2006-2010 BMW 328i 
  • 2006-2010 BMW 325xi 
  • 2006-2010 BMW 330xi 
  • 2006-2010 BMW 328xi 
  • 2006-2010 BMW 335i 
  • 2006-2010 BMW 335xi


The following fault codes are commonly found stored in BMW DME models related to VANOS faults:

  • P0015 Crankshaft  correlation value outside ref range
  • 2A9A Cam sensor, inlet signal invalid for synchronization
  • 2A98 (P0016) Crankshaft intake correlation value outside ref range
  • 2A82 intake VANOS jammed mechanically
  • 2A9B exhaust camshaft sensor signal invalid for synchronization
  • 2A99 (P0017) Crankshaft position sensor and exhaust camshaft correlation value outside reference range
  • 2A87 exhaust VANOS jammed mechanically

Each test step / procedure below is used by the Autologic Live Technical Support Specialists to Assist shops all over the world diagnose BMW VANOS faults. At any point during this procedure you find a fault and correct it, clear VANOS adaptations and recheck the system with a complete road test. 

Proceed through each step until the cause of the fault code(s) is found. 

If you get stuck or are unsure of your test results, Get in touch, we will get that vehicle fixed for you.

Check Oil Level

Low oil level can cause VANOS system oil pressure and volume to drop, causing timing fault codes.

To begin, check engine oil level. You can use your AssistPlus device or check oil level using the instrument panel driver information display / iDrive control.

Oil Level Check using your AssistPlus Video


For step by step instructions, see this article.

Checking engine oil level using the driver information display. Turn the key on with the engine off.


Press the turn signal stalk rocker switch up or down to scroll to OIL.

Press the BC button to display engine oil info

The oil level will be displayed (possible messages):

  • Oil Level OK
  • Oil Level Being Checking (3 – 5 minutes)

  • Oil Level + 1 qts (oil level at minimum, add 1 quart and recheck)

  • >MAX (oil level overfull)

  • INACTIVE (faulty oil level sensor)

Correct oil level as needed, then move to next step.

Inspecting Oil Filter Cap

Remove the oil filter cap and inspect for missing center section.

This photo shows the center section in place (Good Condition)

This photo shows a missing center section (Faulty Condition)

This photo shows the often missing cage, removed from the oil filter cap

Next, using your Assistplus Device follow the VANOS diagnosis test plan that is available for your model

We will move through the tests in order. Pausing to perform additional system and component test.

AssistPlus Test 1

AssistPlus Test 2

Inspect VANOS Solenoid Wiring

Inspect wiring and connections at both VANOS solenoids. Check for oil intrusion, debris or damage to terminals. The VANOS solenoids are located at the front of the cylinder head.

This photo shows the intake and VANOS solenoid electrical connectors

Check for clean and good condition connector as shown here

If connector is found damaged or oil saturated, repair, clean or replace as needed.

Check voltage to VANOS solenoids

VANOS solenoids are supplied 12 volts and controlled via TTL ground pulse from the DME.

Testing the 12 volt supply to solenoid

The VANOS solenoid should have battery volts present with the key on and the engine OFF.

Testing the DME TTL circuit to the VANOS solenoid

The DME side of the circuit should have about 4 volts present with the key on and the engine OFF.

Remove the VANOS solenoids to Inspect

If the fault is only for the intake or exhaust side, remove the Vanos solenoids from the engine. Inspect for dirt or build up. Clean the solenoids and swap them. Reset VANOS adaptation and road test. If the issue follows the solenoid position change, replace the VANOS solenoids.

If the fault is for both intake and exhaust it is recommended to replace both solenoids. Reset adaptation than road test.

VANOS Solenoid locations

VANOS solenoids are located at the front of the cylinder head.

Remove the VANOS solenoids and inspect.

Check that all passages, filters, screens and bores are clean, clear and free from debris.

This photo shows a debris (sludge) filled solenoid that was causing VANOS fault codes.

Inspect Non-Return Valve

If the fault(s) continue check the Non-Return valve located by the Timing Chain tensioner. Make sure the valve is not clogged and the ball and spring do not hang up.

If the fault(s) still return after non-return valve inspection, remove the valve cover and check engine timing.

Non-Return valve is Located Above the Timing Chain Tensioner

Non-Return Valve Location

Remove Non-Return Valve

Unscrew and remove using an Allen bit.

Inspect Non-Return Valve for Debris - Replace if Suspected Dirty - Can't Be Cleaned

AssistPlus Test 3

AssistPlus Test 4

In this test, engine timing components are checked.


First check and confirm the central bolt is tight on both VANOS actuators.

Then, check if mechanical engine timing is correct. Lock engine down using camshaft and crankshaft locking tools. Set engine according to repair information for the vehicle you are working on.


Remove Crankshaft Alignment Hole Plug

Install the crankshaft locking tool

Install Camshaft Locking Tool

Confirm timing is correct and tools are installed correctly. 

If timing was found incorrect, correct engine timing and recheck for faults.

AssistPlus Test 5

In this test the rectangular compression ring and bearing strips are checked.

Remove the valve cover. Secure camshafts and crankshaft in place. Remove the timing chain tensioner.


Remove the camshaft bearing cap(s)

Inspect Sealing Surfaces for Scoring, Wear and Grooves

If the bearing ledge or bearing caps have no sign of wear and faults are still present, replace the VANOS acutaors. 

Clear / Reset Adaptations

Be sure to clear VANOS adaptations any time a repair or fault has been found and recheck the system with a complete road test.


Still nee help diagnosing a VANOS fault on a BMW or MINI vehicle? Get in touch, we will get that vehicle fixed for you.