P0017

What the Code Means

P0017 indicates a mismatch between the crankshaft position and the exhaust camshaft position (Sensor B) on cylinder bank 1. On the N20 engine, this code — like P0016 — points to a stretched timing chain or incorrectly set valve timing. It often shows up alongside P0016 and flags the same underlying problem: worn timing chain components.

How the Affected System Works

The timing system keeps the crankshaft and camshafts in sync. Position sensors (Sensor B on the exhaust camshaft) send signals to the DME, which compares them against reference values. A stretched chain or shifted timing creates a discrepancy, and the DME logs the fault.

Components Involved

• Timing chain
• Timing chain tensioner
• Chain guides and rails
• Crankshaft position sensor
• Camshaft position sensor (exhaust, Bank 1 Sensor B)
• DME (engine control unit)

Symptoms

• Engine:
• Rattling noise on cold start
• Rough idle
• Misfires
• Indicators:
• Check Engine Light on
• When It Shows Up:
• Symptoms are most noticeable on a cold engine and at idle

Diagnosis and Repair

Step 1: Diagnose with ISTA

Connect ISTA or INPA and read the actual valve timing values. Compare them to the nominal values. Watch for companion codes, especially P0016.

Step 2: Visual Inspection of the Timing Chain

Pull the valve cover and inspect the chain, tensioner, and guides. Signs of wear: chain play, damaged plastic guides, metal shavings in the oil.

Step 3: Replace the Timing Chain Kit

If you find wear, replace the timing chain, tensioner, guides, and rails. Use only genuine BMW (OE) parts.

Step 4: Verify Timing Is Set Correctly

After replacement, confirm the timing marks line up and check the timing with ISTA.

Common Diagnostic Mistakes

• Replacing only the sensors without checking the chain — that won't fix it.
• Ignoring the companion code P0016.

Tools You'll Need

• ISTA or INPA
• Timing repair tool set
• Torque wrench

Secondary Damage

Ignoring P0017 can lead to serious consequences:

• Timing chain failure — total engine destruction (bent valves, damaged pistons and cylinder head).
• Tensioner and guide damage — fragments can drop into the oil pan and clog the oil pump.
• Accelerated wear on other components — incorrect valve timing hurts combustion, which leads to overheating and detonation.

Severity: high. If you hear a cold-start rattle, don't drive the car until the fault is fixed. An engine replacement is a very expensive repair, and the total depends on the model and condition.