P0018 on 2010-2011 Saab 9-5 2.8L V6: Stretched Timing Chain Causes and Fixes

What's Unique About the 2010-2011 Saab 9-5

The 2010-2011 Saab 9-5 uses a 2.8L V6 Turbo engine (A28NER) from General Motors, which is part of the GM High Feature V6 family. These engines are notoriously prone to premature timing chain stretching. The engine uses a complex system of three separate timing chains, and the materials of the original chains are a known weak point. As a result, a P0018 code on this specific vehicle is a very strong indicator of a significant mechanical problem rather than a simple sensor failure. GM implicitly acknowledged the issue by releasing updated timing chain kits and TSBs (like 12-06-01-009) for this engine family, and the problem is reported to be less common on models produced after 2012.

Symptoms You May Notice

• Check Engine Light is on
• Engine rattling noise, especially on a cold start
• Rough or unstable idle
• Reduced engine power and poor acceleration
• Engine stalling
• Increased fuel consumption
• Difficulty starting the engine

Most Likely Causes

1. Stretched Timing Chains 🔴 High Probability → Shop Engine Timing Chain The GM-sourced 2.8L V6 engine is widely known for using timing chains that are prone to premature stretching due to their design and material composition. The complex three-chain system exacerbates this issue. This was a known issue across multiple GM brands using this engine.
   How to confirm: A mechanic can use a scan tool to observe the camshaft angle deviation; a persistent deviation greater than 5-8 degrees at idle is a strong indicator. Definitive confirmation requires physical inspection of the chains for slack by removing the timing cover, which is labor-intensive.
   Typical fix: Replacement of all three timing chains, along with all related tensioners and guides. It is critical to replace everything as a complete kit using updated parts. 🎬 Watch: A complete walkthrough of the timing chain replacement process. GM TSB 12-06-01-009 notes that guides should only be replaced if visibly worn.
   Est. part cost: $400-$800 for a high-quality complete kit
2. Failed Timing Chain Tensioner(s) or Guide(s) 🟡 Medium Probability → Shop Engine Timing Chain The hydraulic tensioners and plastic guides wear out over time, and their failure can cause slack in the chain, leading to the same correlation error. This is often accelerated by infrequent oil changes or low oil pressure.
   How to confirm: Visual inspection after removing the timing cover. A rattling noise from the engine that subsides after a few seconds from a cold start is a strong indicator of a failing tensioner.
   Typical fix: This is almost always addressed during a full timing chain kit replacement. It is not recommended to replace only a failed tensioner or guide.
   Est. part cost: $400-$800 (as part of a full kit)
3. Low or Dirty Engine Oil ⚪ Low Probability The camshaft phasing system (VVT) is hydraulic and relies on clean oil at the correct pressure to function. Neglected oil changes can lead to sludge that clogs passages in the VVT solenoids or phasers, preventing them from operating correctly and potentially accelerating chain/guide wear.
   How to confirm: Check the oil level on the dipstick and inspect its condition. If it's low or very dirty, this could be a contributing factor.
   Typical fix: Perform an oil and filter change using the correct specification oil (Dexos-approved). However, if the chain has already stretched, this will not solve the P0018 code.
   Est. part cost: $50-$100
4. Faulty Camshaft Position Sensor ⚪ Low Probability → Shop Engine Camshaft Position Sensor
   How to confirm: Swap the Bank 2 intake camshaft sensor with the Bank 1 intake sensor. If the code changes to P0016 (the Bank 1 equivalent), the sensor is bad. If the P0018 code returns, the sensor is not the cause.
   Typical fix: Replace the faulty sensor.
   Est. part cost: $40-$90

Rare But Worth Checking

• Faulty Camshaft Phaser / Actuator: → Shop Engine Camshaft The VVT actuator on the camshaft can become stuck due to debris or internal failure. This is less common than chain stretch but can cause the same code. Diagnosis involves scan tool data analysis and potentially manual inspection.
• Faulty VVT Solenoid (Oil Control Valve): The solenoid that directs oil to the phaser can fail or become clogged. It can be tested for resistance (typically 6.9-7.9 ohms) and function, and is easier to replace than a phaser or timing chain.
• Slipped Camshaft Reluctor Ring: → Shop Engine Camshaft In some rare cases on the High Feature V6 family, the embossed reluctor ring that the camshaft position sensor reads can physically move or slip on the camshaft itself, causing a correlation error even with perfect mechanical timing. This is difficult to diagnose and often requires camshaft replacement.

Diagnosis Steps

1. Verify Oil Level and Condition: Ensure the engine oil is full and clean. If not, perform an oil change and clear the code to see if it returns.
2. Scan for All Codes: Check for other related codes (like P0016, P0008, P0009) that can help confirm a systemic timing issue.
3. Analyze Live Data: Use a professional scan tool to monitor the desired vs. actual camshaft position angles for Bank 2. A significant, persistent deviation (often >5 degrees) indicates a timing problem.
4. Test the Camshaft Position Sensor: As a simple check, swap the Bank 2 intake cam sensor with the Bank 1 intake cam sensor. Clear codes and see if the fault moves to Bank 1 (P0016). If it does, the sensor is faulty. If P0018 returns, the problem is mechanical.
5. Inspect VVT Solenoids: The oil control solenoids can be removed and tested for mechanical binding and correct electrical resistance (approx. 7 ohms).
6. Perform Mechanical Timing Inspection: This is the definitive step. A technician will need to remove the engine timing cover to physically inspect the timing chains for slack, check the tensioners for proper operation, and verify that all timing marks align correctly. This is a labor-intensive process.

Parts You'll Likely Need

• Engine Timing Chain Kit (OEM #GM 12651450 (Reference kit for 2008-2012 HFV6, confirm application)) — This is the most common cause of P0018 on the 2.8L V6. A complete kit ensures all worn components (chains, guides, tensioners) are replaced for a lasting repair.
  Trusted brands: Cloyes, INA, HEPU
  OEM price range: $600-$1000
  Aftermarket price range: $400-$800
• Camshaft Position Sensor — While rarely the root cause, a sensor can fail. It's a common misdiagnosis but should be ruled out.
  Trusted brands: Delphi, Bosch, Hitachi
  OEM price range: $70-$120
  Aftermarket price range: $40-$90

Related Codes That Often Appear With This One

• P0016 — Crankshaft/Camshaft correlation error for Bank 1. If both P0016 and P0018 are present, it strongly points to an issue with the primary timing chain that serves both banks.
• P0008 — Engine Positions System Performance Bank 1. This is a more general timing code that, when seen with P0018, reinforces the diagnosis of a major timing system failure, likely a stretched primary chain. This code is specifically mentioned in GM TSB 12-06-01-009.
🎬 See: How these specific codes relate to GM's extended warranty.
• P0009 — Engine Positions System Performance Bank 2. Similar to P0008, its presence points to a significant timing misalignment and is also covered by GM TSB 12-06-01-009.

Technical Service Bulletins (TSBs) & Recalls

• GM TSB 12-06-01-009: Titled 'Information on High Feature V6 Timing Chain Kits and Chain Guide Replacements, DTCs P0008, P0009, P0016, P0017, P0018 and/or P0019'. This is the primary GM document acknowledging the stretched chain issue and providing the official repair procedure and parts list for technicians.

Platform-Specific Known Issues

• The 2.8L V6 Turbo (A28NER/LP9) engine has a well-documented history of premature timing chain failure. The issue is not a matter of 'if' but 'when' for many owners, sometimes occurring at surprisingly low mileage.
• There has never been a safety recall issued for this timing chain problem, meaning the owner is fully responsible for the expensive repair costs.
• GM issued Technical Service Bulletin 12-06-01-009 covering multiple DTCs including P0018, acknowledging stretched chains as the cause and providing repair guidance for technicians.

Mechanic-Grade Diagnostic Values

• Camshaft Actuator (VVT) Solenoid Resistance — expected: 6.9-7.9 Ohms. Failure: A reading outside this range indicates a faulty solenoid coil.
• Scan Tool Cam/Crank Correlation Angle — expected: Less than 5 degrees of deviation at idle.. Failure: A persistent deviation greater than 9 degrees is a common threshold for setting the P0018 code on GM vehicles.

Scan Tool Commands That Help

• GM Tech2 / GDS2 or equivalent: VVT Actuator Test / OCV Control — Use this bidirectional command with the engine idling to manually activate the Bank 2 intake VVT solenoid. A functional solenoid and clear oil passages will cause the engine to stumble or run rough. If there is no change in engine operation, it points to a stuck solenoid, a clogged oil passage, or a wiring issue.
• GM Tech2 / GDS2 or equivalent: Crankshaft Position Variation Learn — This procedure is mandatory after replacing a crankshaft, crankshaft position sensor, or ECM. It calibrates the fine variations of the crankshaft reluctor wheel to the ECM to prevent false timing codes like P0315, which can sometimes appear after major timing work.

Wiring & Ground Locations

• G7 — On a bracket at the front of the left-hand side of the engine.. This is a primary engine sensor ground point. Corrosion or a loose connection here can cause erratic signals from the camshaft and crankshaft position sensors, potentially leading to a false correlation code.
• G25 — Main battery ground cable connection point on the gearbox.. A poor main ground connection at the transmission can affect the entire engine management system, causing unpredictable electrical issues and sensor faults.
• Engine Control Module (ECM) — Located in the right rear of the engine compartment.. Knowing the physical location is critical for inspecting the main harness connector for corrosion, damage, or loose pins, which could interrupt the signals from the cam/crank sensors.

OEM Part Supersession History

• GM 12651450 → 12700436 / 12693218 — GM updated the timing chain kits multiple times to improve the durability of the chains and address the premature stretching issue. The newer kits contain the improved design.
  Heads up: While all kits are for the HFV6 family, it is critical to use the latest available part number (e.g., 12693218 or 12700436) to get the most durable, updated chains. Using old stock or an incorrect early-design kit will likely lead to a repeat failure.

Model Year Variations Within This Range

• 2010-2011: Aero models with the 2.8T V6 were equipped with GM's 'HiPer Strut' front suspension, whereas the 2.0T models used a conventional MacPherson strut design. This does not affect the P0018 code but is a notable platform difference.

Diagnostic Flowchart

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 — This is the Bank 1 equivalent of P0018 (Crankshaft Position - Camshaft Position Correlation). It frequently appears alongside P0018 when the primary timing chain stretches, affecting both banks, and is explicitly covered under GM TSB 12-06-01-009.
• P0008 — Engine Position System Performance Bank 1. This code indicates a systemic timing issue and is often triggered simultaneously with P0018 due to the same stretched timing chain condition outlined in TSB 12-06-01-009.
• P0009 — Engine Position System Performance Bank 2. Like P0008, this is a companion code that confirms a mechanical timing deviation on Bank 2, pointing directly to chain stretch or tensioner failure.
• P0017 — Crankshaft Position - Camshaft Position Correlation Bank 1 Sensor B. This is another correlation code covered under GM TSB 12-06-01-009 that can trigger when the complex three-chain system develops slack.
• P0019 — Crankshaft Position - Camshaft Position Correlation Bank 2 Sensor B. This code shares the exact same root causes as P0018 (stretched chains, failed tensioners) and is included in the same GM technical service bulletin.

Frequently Asked Questions