EN

Severity: Moderate Code type: Generic (all makes)

P0015 Code: "B" Camshaft Timing Over-Retarded (Bank 1)

The bank 1 exhaust cam sits later than commanded; a stretched chain or stuck exhaust phaser is typical.

At a glance

Severity: 3/5 – Moderate3/5

Severity: Moderate

Meaning
"B" Camshaft Timing Over-Retarded (Bank 1)
System
Fuel & Air Metering · Powertrain
Safe to drive?
With caution
Typical repair cost
$60–$3,500
DIY difficulty
Moderate

On most dual-VVT engines the exhaust camshaft (camshaft B) parks at its most advanced position, held there by a spring and a locking pin, and the PCM retards it with oil pressure at part load to keep some exhaust gas in the cylinder. P0015 sets when the measured exhaust cam angle stays later than the target for too long. Two very different problems produce that result: oil keeps the phaser pushed to retard because the control solenoid sticks or the phaser can't return, or the timing chain has stretched, which makes the cam read late no matter what the phaser does. BMW and MINI engines of the N-series and Prince families, and GM four- and six-cylinders known for chain wear, are frequent sources. Telling the two apart early saves a lot of money, because a stretched chain only gets worse.

Can I keep driving? The car usually runs, with a rougher idle and weaker low-speed torque. If you hear a rattle from the timing chain area at start-up, keep driving to a minimum: a chain that jumps a tooth can bend valves.

How to read P0015

How to read P0015P10203154
  1. P Powertrain
  2. 0 Generic (SAE)
  3. 0 Fuel/air & emissions (aux.)
  4. 15 Specific fault

Symptoms

  • Check engine light, often with P0017 or P0016 stored as well
  • Rough idle and a lazier pull from low rpm
  • Rattle or whine from the front or rear of the engine at cold start
  • Slightly higher fuel consumption
  • Occasional stalling when coming to a stop on some engines

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. Timing chain stretched, or its tensioner or guides worn, making the exhaust cam read late 30%
  2. Exhaust VVT/VANOS solenoid sticking in the retard position or with a clogged screen 24%
  3. Exhaust phaser return spring broken or lock pin not engaging 16%
  4. Low oil level, sludge or wrong viscosity slowing the phaser's return 14%
  5. Exhaust cam sensor, its tone wheel or wiring giving a delayed edge 10%
  6. Cam timing set incorrectly after previous timing work 6%

Diagnosis step by step

Diagnostic flow: P00151Check oil level and service history2Compare both cams at a warm idle3Command the exhaust phaser4Inspect or swap the exhaust solenoid5Measure timing chain stretch6Check the exhaust cam sensor signal

  1. Check oil level and service history

    Top up and note when the oil was last changed and which grade was used. Phasers that return by spring and oil flow react badly to low or sludged oil, and a proper oil change is a cheap first step.

    Tools: Flashlight

  2. Compare both cams at a warm idle

    With the engine warm and VVT inactive at idle, read the actual intake and exhaust cam positions or their deviation from target. If both cams read several degrees late by a similar amount, suspect chain stretch; if only the exhaust cam is late, focus on its solenoid and phaser.

    Tools: OBD-II scanner

  3. Command the exhaust phaser

    Use bi-directional control to command exhaust retard and then release it. The actual angle should follow and return to its parked position within about a second. A cam that goes but won't come back points to a sticking solenoid or a weak return spring.

    Tools: OBD-II scanner

  4. Inspect or swap the exhaust solenoid

    Remove the exhaust VVT/VANOS solenoid and check its screen and seals for debris or damage. On many engines, including BMW N-series, the intake and exhaust solenoids are identical, so swapping them shows whether the fault moves to the intake side.

    Tools: Screwdriver, Flashlight, OBD-II scanner

  5. Measure timing chain stretch

    Use the manufacturer's method: tensioner piston extension, a cam-to-crank offset value, or locking the crankshaft at top dead center and checking whether the camshaft alignment tools still fit. A chain beyond the limit must be replaced with its guides and tensioner.

    Tools: Flashlight, Torque wrench

  6. Check the exhaust cam sensor signal

    If mechanical timing is correct, scope the exhaust cam and crank signals together. A distorted or late edge from the sensor or a damaged tone wheel can mimic a retarded cam.

    Tools: Multimeter, OBD-II scanner

Where the parts are

Ignition: coils and spark plugs per cylinder – P00151234567
Ignition: coils and spark plugs per cylinder
  1. 1Ignition coil
  2. 2Spark plug
  3. 3Fuel injector
  4. 4Camshaft sensor
  5. 5Crankshaft sensor
  6. 6Engine computer (ECM)
  7. 7Intake manifold

Repair options & costs

RepairDIY?Estimated cost
Oil and filter change with the specified grade Yes $60–$150
Replace exhaust VVT/VANOS solenoid Yes $120–$380
Replace exhaust camshaft phaser No $600–$1,500
Timing chain kit with guides and tensioner No $1,200–$3,500

Rough US estimates for parts and labor; shop rates vary by region. Not a quote.

Notes by brand

BMW

The N20 and N26 four-cylinders in the 3 and 5 Series and X-models are known for timing chain guide wear, and a chain rattle at cold start with P0015 is a warning sign to act on. On six-cylinders such as the N52 and N55, a sticking exhaust VANOS solenoid is the more common cause, and the identical intake and exhaust solenoids make a swap test easy. MINI Cooper models with the Prince engines show the same chain-stretch pattern.

Chevrolet

GM four- and six-cylinder engines with timing chains, such as the 2.4 Ecotec and the 3.6 V6, are known for chain stretch. When P0015 shows up together with P0008, P0016 or P0017, measure the chain before replacing any solenoid.

Field data

Mercedes-Benz 2 C-Class, E-Class

Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.

Emissions / smog test impact

Will fail

P0015 lights the check engine lamp, so the car fails an OBD-II emissions test. After the repair, clear the code and drive a few days so the monitors report ready.

Frequently asked questions

What does over-retarded mean for an exhaust cam?

The exhaust valves open and close later than the PCM wants. The PCM commands some retard deliberately at part load, but P0015 means the cam went further or stayed there longer than allowed.

How do I know if it's the chain or the solenoid?

Look at both cams at a warm idle. A stretched chain makes both intake and exhaust read late, while a stuck exhaust solenoid or phaser only affects the exhaust cam. A chain rattle at start-up also points to the chain.

Will a new VANOS or VVT solenoid fix it?

Only if the solenoid is the cause. If the chain has stretched, the code comes back quickly, so check chain stretch before buying parts.

Is P0015 urgent?

If it's a solenoid, it's mostly a drivability and emissions issue. If the chain is stretched, it's urgent, because a chain that jumps teeth can cause serious engine damage.

Sources