What Size Gap Do Spark Plugs Need on a 2009 Audi A4 Quattro?

The correct spark plug gap for most 2009 Audi A4 quattro models is typically around 0.028–0.032 inches (0.7–0.8 mm), with many OEM-style plugs coming pre-gapped near 0.032 inches (0.8 mm). However, the exact specification can vary by engine code and plug type, so it’s important to verify against the owner’s manual, under-hood emissions label, or the spark plug manufacturer’s catalog.

Understanding the 2009 Audi A4 Quattro Spark Plug Gap

The 2009 Audi A4 quattro was sold mainly with turbocharged four-cylinder engines in many markets, and these engines are sensitive to correct spark plug gap. While most modern, manufacturer-approved plugs come pre-gapped and ready to install, checking and confirming the gap helps ensure proper combustion, smoother idle, and reduced misfires, especially as the car ages.

Typical Factory-Style Gap Specification

For commonly used OEM or OEM-equivalent spark plugs in a 2009 Audi A4 quattro (such as NGK, Bosch, and other major brands that cross-reference to Audi/VW part numbers), the recommended gap is usually:

• Approximately 0.028–0.032 inches
• Approximately 0.7–0.8 millimeters
• Most OEM-spec turbocharged applications tend to be near 0.032 inches (0.8 mm)

In practice, many installers and parts catalogs will list 0.032 in (0.8 mm) as the working spec, but staying anywhere within the 0.028–0.032 in range that your manual or plug maker supports is generally acceptable for stock engines.

Why Spark Plug Gap Matters on the A4 Quattro

Spark plug gap is the distance between the center electrode and the ground electrode. On a turbocharged Audi engine, this distance must be precisely controlled. Too wide a gap can cause misfires under boost; too tight a gap can reduce combustion efficiency and performance.

Effects of Incorrect Gap

The following points explain how incorrect spark plug gap can affect a 2009 Audi A4 quattro’s performance and reliability.

• Too wide a gap: Can lead to misfires under load, hesitation, rough idle, and in some cases, trouble codes for ignition misfire (often noticeable on turbo engines under acceleration).
• Too narrow a gap: May cause a weaker spark and incomplete combustion, reducing fuel efficiency and slightly dulling throttle response.
• Ignition coil stress: Persistent misfires from an improper gap can overwork the ignition coils, which are already a known wear item on many Audi/VW engines.
• Emissions impact: Misfires and incomplete combustion can increase emissions and may eventually trigger a Check Engine Light (CEL), potentially causing inspection failures in regions with emissions testing.

Keeping the spark plug gap within the recommended range helps preserve smooth running, avoids unnecessary strain on ignition components, and maintains fuel economy and emissions performance.

How to Confirm the Correct Gap for Your Specific Engine

Because the 2009 A4 quattro may have different engine codes and regional variations, the safest approach is to confirm the exact specification for your particular car rather than relying solely on a generic value.

Sources for the Official Specification

The following sources can help verify the correct spark plug gap for your specific 2009 Audi A4 quattro engine and market.

1. Owner’s manual: Often lists spark plug type and may provide the gap specification or a note that plugs come pre-gapped.
2. Under-hood emissions or tune-up label: Some vehicles list plug and gap information on a sticker in the engine bay.
3. Dealer or official Audi service information: A dealer can look up your VIN and give the exact OEM spec for the engine code.
4. Spark plug manufacturer catalog: NGK, Bosch, and others provide vehicle-specific plug numbers and recommended gap values online.
5. Trusted service manuals: Factory workshop manuals or high-quality aftermarket manuals often list the specified gap and plug part numbers.

Checking at least one official or high-quality reference is important, especially if your A4 has a less common engine variant or has been sold in a region with different specifications.

Pre-Gapped vs. Manually Gapped Plugs

Many of the platinum or iridium plugs recommended for modern Audi engines, including the 2009 A4 quattro, come pre-gapped. However, the term “pre-gapped” does not guarantee the gap remained perfect after shipping or handling, so it’s generally wise to inspect it.

Best Practices When Installing Spark Plugs

The following practices help ensure that your spark plugs are gapped correctly and installed without damage.

• Measure the gap: Use a proper wire or blade-style feeler gauge to verify that the gap is within the 0.028–0.032 in (0.7–0.8 mm) range, or the specific figure provided by your documentation.
• Adjust carefully: If adjustment is needed, bend only the ground electrode, and do so very gently to avoid cracking the insulator or damaging fine-wire electrodes.
• Handle iridium and fine-wire plugs with care: These plugs are more delicate at the tip, and heavy-handed gapping tools can damage the precious metal electrode.
• Follow torque specs: Once gapped, tighten the plugs using the torque specification from Audi or the plug manufacturer to avoid overtightening or under-tightening.

By confirming the gap and installing the plugs correctly, you maximize plug life, protect your ignition coils, and keep the engine running as Audi intended.

Summary

For a 2009 Audi A4 quattro, the typical spark plug gap specification is in the region of 0.028–0.032 inches (0.7–0.8 mm), with 0.032 in (0.8 mm) being a common practical target for OEM-style plugs. Because minor variations can exist between engine codes and markets, confirming the exact value via the owner’s manual, an under-hood label, dealership information, or the spark plug manufacturer’s catalog is recommended. Ensuring the plugs are correctly gapped and carefully installed helps maintain smooth performance, reliability, and fuel efficiency in this turbocharged Audi platform.

What is the spark plug Gap on a 2009 Audi a3?

Notes: Iridium IX spark plug. Gap 0.032″.

Do Audi spark plugs come pre-gapped?

If you order the specific part number for your car (whether OEM or OE), it should be pre-gapped.

What is the spark plug Gap on an Audi A4?

The Audi A4 spark plug gap is generally 0.032 inches for stock engines, but it is often smaller for turbocharged or modified engines, typically ranging from 0.024 to 0.028 inches. Always check your vehicle’s specific requirements, as the gap can vary by model year and engine configuration. 
You can watch this video to learn how to gap spark plugs on a 2017 Audi A4: 1mDIY DetailYouTube · Nov 8, 2019
Spark plug gap recommendations

• Stock turbocharged engines: The gap is typically set to 0.032 inches. 
• Tuned or high-boost engines: A smaller gap, such as 0.028 inches or slightly lower, is recommended to prevent misfires under high pressure. 
• Specific models:
  • Gen 3 TSI (MQB): Gap between 0.024 to 0.026 inches. 
  • Supercharged 3.0T (B8): Gap to 0.028 inches. 
  • Turbocharged 2.9T and 3.0T (B9): Gap to 0.024 to 0.026 inches using fresh factory plugs. 

How to adjust the gap

• Use a spark plug gap tool: This tool can be used to measure and adjust the gap before installing the plug.
• To contract the gap: Gently push the ground strap against the electrode. Be careful not to apply too much force and damage the plug.
• To expand the gap: Use the tool to bend the ground strap away from the electrode. 

Why the gap matters

• An incorrect gap can lead to a poor spark, which can cause misfires, rough idling, and decreased fuel economy. 
• Modifications that increase boost pressure require a tighter gap because the increased pressure makes it harder for the spark to jump across the gap. 

This video explains how to gap spark plugs for a 2009-2016 Audi A4 2.0 TFSI: 1mHow to AutomotiveYouTube · Jul 20, 2017

What is the spark plug Gap on a 2010 Audi 2.0 T?

0.032″
Gap 0.032″. Spark plug, double platinum.