P0018 on 2004-2010 Audi A8 4.2L V8 (BVJ): Crank/Cam Correlation Causes and Fixes

What's Unique About the 2004-2010 Audi A8

The 4.2L V8 (BVJ) engine in the D3 generation A8 is an FSI (Fuel Stratified Injection) motor with a complex timing chain system located at the rear of the engine, against the firewall. Unlike earlier belt-driven Audi V8s, any issue with the chains, guides, or tensioners on this engine requires removing the entire engine for service. Because of this design, a P0018 code is often a precursor to a catastrophic and extremely expensive timing system failure, a known issue on these engines.

Symptoms You May Notice

• Check Engine Light is on
• Rough or uneven idle
• Reduced engine power and acceleration
• Engine is hard to start, requiring longer cranking
• Rattling noise from the rear of the engine, especially on cold startup, lasting 1-3 seconds
• Engine stalling
• Failure of emissions testing for vehicle registration

Most Likely Causes

1. Stretched Timing Chain / Failed Timing Chain Tensioners 🔴 High Probability → Shop Engine Timing Chain The BVJ engine's timing components, particularly the plastic-coated guides and hydraulic tensioners, are known wear items. The long chains stretch over time, and tensioners can lose hydraulic pressure, allowing slack. This is a well-documented issue across all Audi 4.2L FSI platforms.
   How to confirm: A qualified technician will use a scan tool (like VCDS) to read camshaft adaptation values (measuring block 093). A total deviation per bank exceeding -7 or -8 degrees strongly indicates significant chain stretch. A definitive diagnosis requires engine removal and physical inspection of the chains, guides, and tensioners.
   Typical fix: Complete replacement of all timing chains, tensioners, and guides. This is an engine-out procedure. 🎬 See this walkthrough of the complex BVJ timing chain replacement The job is extremely labor-intensive, often quoted at 40-55 hours.
   Est. part cost: $1500-$2500
2. Faulty Camshaft Position Sensor (Bank 2 Intake) 🟡 Medium Probability → Shop Engine Camshaft Position Sensor Sensors can fail electronically over time, sending incorrect or no data to the ECM. This is a common diagnostic step before condemning the timing chains.
   How to confirm: Swap the Bank 2 intake camshaft sensor with the Bank 1 intake sensor. Clear codes and run the engine. If the fault code changes to P0016 (Bank 1 correlation), the sensor is bad. In some cases, a failed sensor can cause the VCDS measuring block for that cam's phase position to be blank.
   Typical fix: Replace the faulty camshaft position sensor. 🎬 Watch: How to replace the camshaft position sensor
   Est. part cost: $30-$185
3. Faulty Camshaft Adjuster Solenoid (VVT Solenoid) ⚪ Low Probability → Shop Engine Camshaft These solenoids control oil flow to the camshaft phasers. They can become clogged with sludge from infrequent oil changes or fail electronically, preventing proper camshaft adjustment.
   How to confirm: Test the solenoid's resistance with a multimeter (typically 5.0-8.0 ohms). A technician can command the solenoid with a scan tool to check for a response. Swapping the Bank 1 and Bank 2 intake solenoids is another diagnostic step; if the code changes to P0016, the solenoid is the culprit.
   Typical fix: Replace the Bank 2 intake camshaft adjuster solenoid.
   Est. part cost: $50-$150
4. Low Engine Oil Level or Incorrect Oil ⚪ Low Probability The variable valve timing system and chain tensioners are hydraulically operated. Insufficient oil pressure due to low level, incorrect viscosity, or oil degradation can prevent the camshaft adjusters and tensioners from working correctly.
   How to confirm: Check the engine oil level and condition. Ensure the oil meets Audi's specific VW 502 00 specification. An oil change is a cheap first step if the history is unknown.
   Typical fix: Perform an oil and filter change using the correct OEM-spec oil.
   Est. part cost: $80-$150

Rare But Worth Checking

• Failed Camshaft Adjuster (Phaser): → Shop Engine Camshaft The mechanical adjuster on the camshaft itself can fail, but this is less common than chain, tensioner, or solenoid issues. This would also likely require an engine-out service to replace.
• Damaged Crankshaft Reluctor Wheel: → Shop Engine Crankshaft The tone ring that the crankshaft position sensor reads can be damaged or shift, but this is a very rare failure.
• Wiring Harness Issue: A break or short in the wiring to the camshaft position sensor or VVT solenoid could cause the code. An owner on AudiWorld reported a blank VCDS reading for the cam sensor and suspected a harness or fuse issue after replacing sensors didn't solve it.

Diagnosis Steps

1. Read all fault codes using an Audi-specific scan tool (like VCDS or OBD-Eleven). Note any other codes present.
2. Check engine oil level and condition. If low, dirty, or of unknown specification, perform an oil and filter change with OEM-spec oil (VW 502 00), clear codes, and see if the fault returns.
3. With VCDS, navigate to Engine (01) -> Measuring Blocks (08) -> Group 093. Observe the 'Camshaft adaptation' values for Bank 1 and Bank 2 at warm idle. Add the intake and exhaust values for each bank. If the total for Bank 2 (or Bank 1) is more negative than -8 degrees, this is a strong indication of a stretched timing chain.
4. Listen for a metallic rattling noise from the back of the engine on a cold start. A 1-3 second rattle is a classic sign of failing hydraulic tensioners losing pressure overnight.
5. If timing values are borderline (e.g., -4 to -7 degrees), proceed with electrical diagnosis. Swap the Bank 2 intake camshaft position sensor (Sensor 'A') with the identical sensor on Bank 1. If the fault code changes to P0016, the sensor is faulty.
6. Test the Bank 2 intake camshaft adjuster solenoid (N318). Check its resistance (should be 5.0-8.0 ohms) and consider swapping it with the Bank 1 solenoid to see if the fault follows.
7. If all sensors and solenoids test good but the code persists and/or the measuring block 093 values are out of spec, the issue is confirmed to be mechanical (stretched chain, failed guides/tensioners). This requires a professional diagnosis involving engine removal for visual inspection and repair.

Parts You'll Likely Need

• Timing Chain Kit (OEM #Various, e.g., 079109229L (Main Chain)) — This is the most probable cause of P0018 on a higher-mileage BVJ engine. A complete kit includes all chains, guides, tensioners, and seals.
  Trusted brands: Genuine Audi, Iwis (OEM supplier), Febi Bilstein
  OEM price range: $1500-$2500
  Aftermarket price range: $800-$1500
• Camshaft Position Sensor (OEM #07L905163C) — A failed sensor can send incorrect data, causing a correlation fault. It's a common point of failure and a relatively inexpensive part to replace as a diagnostic step.
  Trusted brands: Bosch (OEM supplier), Genuine Audi
  OEM price range: $100-$185
  Aftermarket price range: $30-$90
• Camshaft Adjuster Solenoid (OEM #06E109257P) — This solenoid controls the variable valve timing. If it gets stuck or fails, it can prevent the camshaft from adjusting properly, triggering the code.

Related Codes That Often Appear With This One

• P0019 — Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor 'B'). This refers to the exhaust camshaft on the same bank, often triggered by the same root cause like a stretched timing chain affecting the entire bank.
• P0346 — Camshaft Position Sensor 'A' Circuit Range/Performance (Bank 2). This points more specifically to a problem with the sensor's circuit or the sensor itself, and could appear alongside P0018.
• P0016 — Crankshaft Position - Camshaft Position Correlation (Bank 1). If seen with P0018, it could indicate a problem with the main timing chain affecting both banks, a faulty crankshaft position sensor, or severe, widespread wear.

Platform-Specific Known Issues

• The timing chain system on the 4.2L FSI (BVJ) engine is located at the rear of the engine block, requiring engine removal for service. This makes the repair extremely labor-intensive and expensive, often costing more than the value of the car.
• A startup rattle from the rear of the engine is a tell-tale sign of impending timing component failure. Audi issued TSB 2039995/1 for this noise, recommending the replacement of upper chain tensioners with improved parts.
• Due to the high cost of the timing chain repair, a P0018 code on a high-mileage D3 A8 often leads to the vehicle being considered 'mechanically totaled' by its owner.

Mechanic-Grade Diagnostic Values

• Camshaft Adjuster Solenoid (N318) internal resistance — expected: 5.0 to 8.0 Ohms at ~20°C. Failure: A reading outside this range, or an open/short circuit, indicates a faulty solenoid.
• Camshaft Position Sensor (G163) supply voltage — expected: Approx. 5.0 Volts. Failure: No voltage or significantly lower voltage suggests a wiring or ECM issue.
• Camshaft Position Sensor (G163) signal voltage (while cranking) — expected: Should pulse or switch between ~5V and 0V as the engine rotates.. Failure: A constant voltage or no voltage indicates a failed sensor.
• Wiring harness resistance from solenoid connector to ECM connector — expected: Max 1.5 Ohms. Failure: Higher resistance indicates corrosion or a break in the wire.

Scan Tool Commands That Help

• VCDS (VAG-COM): Engine -> Output Tests — This function can be used to sequentially activate each camshaft adjuster solenoid. The technician should listen for an audible 'click' from the solenoid being tested. A lack of a click from the Bank 2 intake solenoid (N318) when commanded indicates it is stuck or has failed, even if its electrical resistance is correct.
• VCDS (VAG-COM): Engine -> Measuring Blocks -> Group 093 — This is the primary diagnostic step to check for mechanical timing stretch. A value more negative than -8 degrees on Bank 1 or Bank 2 strongly suggests a stretched chain or failed tensioner requiring mechanical repair.

Wiring & Ground Locations

• Ground Point 18 — On the engine block itself.. A corroded or loose main engine ground can cause erratic behavior and incorrect readings from all engine sensors, including the cam and crank sensors.
• Ground Strap 3 — Connects the engine to the body/chassis.. This is a critical ground path. If compromised, the starter may seek a ground path through smaller sensor ground wires, potentially damaging them or causing voltage drops that lead to correlation faults.
• Ground Point 13 — On the right side of the engine compartment.. This is a chassis ground point that serves various components in the engine bay. Ensuring it is clean and tight is part of good diagnostic practice for any electrical fault.
• Bank 2 Camshaft Position Sensor (G163) — Located on the driver's side (Bank 2) at the rear of the cylinder head, near the firewall. Access is difficult.. This is the specific sensor ('Sensor A') for code P0018. Its location makes inspection of its connector and wiring for damage a challenging but necessary step.

Real Owner Repair Stories

• AudiWorld Forums user 'Timppa811' (2008 Audi A6 4.2L FSI (BVJ)) — P0018 and misfires on cylinders 5-8, engine shaking badly. VCDS showed no reading for Bank 2 cams in measuring block 93.
  ❌ Tried (didn't work) Replaced a jammed Bank 2 intake cam adjuster., Cleaned and tested all solenoids., Replaced a cracked upper chain guide., Swapped camshaft position sensors between banks.
  ✅ What actually fixed it The user discovered the Bank 2 timing had jumped by two teeth. The cause was a failed (likely collapsed) timing chain tensioner. The final fix was replacing the failed tensioner.
• AudiWorld Forums user 'scooterfree62' (2007 Audi A8L 4.2L (BVJ) with 213,000+ miles) — P0018, rough idle, and a rubbing/rattle noise on startup that then disappeared. VCDS showed the 'phase position bank 2 intake' field as completely blank.
  ❌ Tried (didn't work) Swapping intake solenoids between banks., Replacing both Bank 2 cam sensors with new OEM parts.
  ✅ What actually fixed it The thread ends without a definitive confirmed fix from the original poster. However, another user with the identical symptom (blank field in VCDS) chimed in, suspecting a wiring harness or fuse issue after new sensors didn't resolve the problem. This highlights that a blank reading (vs. an out-of-spec reading) may point towards an electrical circuit failure rather than just a bad sensor.
• NHTSA ODI #11233069 — An owner reported that at approximately 63,000 miles, the check engine light illuminated with code P0018. The vehicle subsequently failed an emissions test required for license renewal.

OEM Part Supersession History

• 077109087C, 077109087E → 077109087P — These part numbers refer to the cam chain tensioner for the earlier, belt-driven 4.2L V8 (like the BFM), not the chain-driven BVJ. This is a critical distinction.
  Heads up: Parts for the earlier BFM engine are often mistakenly listed for the BVJ. The tensioners are not interchangeable. The BVJ uses individual tensioners and guides as part of a larger rear-mounted assembly. Always verify parts by VIN for the FSI engine.
• N/A → 079109217J, 079109217S, etc. — The FSI timing system has numerous components. For example, 079109217S is a left upper tensioner for the cam-to-cam chain. There have been multiple revisions of these parts over the years to improve durability.
  Heads up: It is critical to order a complete, matched timing kit for the BVJ engine. Using a mix of old and new revision parts, or parts from different manufacturers, can lead to premature failure. The RS4 metal guides are a common upgrade.

Model Year Variations Within This Range

• 2004-2006 vs 2006-2010: The most significant variation is the engine itself. Early D3 A8s (2004-2006) used the 4.2L BFM engine, which is port-injected and has a timing BELT at the front. The P0018 fault is primarily an issue on the later 2006-2010 models with the direct-injection (FSI) BVJ engine, which has the complex timing CHAIN system at the rear.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Adaptive Air Suspension Failure 🔴 High — Very common on vehicles over 80,000 miles. Leaking air springs (struts) cause the compressor to overwork and fail. Sagging at one corner, especially overnight, is a key symptom.
• Intake Valve Carbon Buildup 🟠 Medium — Inevitable on all FSI (direct injection) engines, including the 4.2L V8. Symptoms like rough idle, hesitation, and loss of power typically appear every 60,000-80,000 miles. Requires manual cleaning (walnut blasting).
• MMI System Malfunction 🟠 Medium — Commonly reported issue where the MMI screen fails to open, goes blank, or the system randomly reboots. Often caused by a failure in one of the modules on the fiber optic MOST ring, a blown fuse, or a faulty control head.
• Intake Manifold Swirl Flap Linkage Failure 🟡 Low — The plastic linkages that control the intake manifold swirl flaps can wear out and break, leading to a loss of low-end torque and a check engine light. This is a less severe issue than on the TDI models but still occurs. (Ref: Repair kits are available (e.g., 059 198 212 for TDI, similar principles apply) which are much cheaper than replacing the entire manifold.)
• Trunk Lid Motor Failure 🟡 Low — The electric motor for the automatic trunk lid is a known weak point and often fails, preventing the trunk from opening or closing automatically.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this specific fault code, using used parts is highly discouraged for anything other than a simple sensor swap for diagnostic purposes. Given the high labor cost of accessing internal engine components, the risk of a used part failing is too great. A used camshaft position sensor or VVT solenoid from a low-mileage, verified running donor car could be used for testing, but it's recommended to install a new part for the final repair.

Donor-vehicle mileage cap: roughly under 50000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Verify the donor vehicle was running without timing-related fault codes before being dismantled.
• For sensors/solenoids, inspect the connectors for corrosion or damage.
• Avoid parts from engines that show signs of heavy oil sludge or poor maintenance.

OEM-only on this vehicle (don't cheap out):

• Timing Chains
• Timing Chain Tensioners
• Timing Chain Guides
• Camshaft Adjusters (Phasers)

Aftermarket brands forum-validated for this vehicle:

• Iwis (often the OEM supplier for chains)
• Bosch (OEM supplier for sensors)
• INA (OEM supplier for tensioners and bearings)
• Febi Bilstein (offers complete kits)

Brands owners have reported issues with on this vehicle:

• Unbranded, low-cost timing kits from online marketplaces. The labor for this job is far too expensive to risk using parts of unknown quality that could fail prematurely.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0016 — The Bank 1 equivalent of P0018; it often appears if a faulty sensor or solenoid is swapped from Bank 2 to Bank 1 during diagnosis.
• P0011 — Related to camshaft timing over-advanced; can occur when the camshaft adjuster solenoids (N318) fail or become clogged with sludge.

Frequently Asked Questions