Audi Audi RS5 2017-present Emissions & Sensor Bolt Torque Specifications
This page provides detailed torque specifications for the various emissions sensors bolts on the 2017-Present Audi RS5, including lambda, NOx, and pressure sensors.
Important Information
Safety guidelines and reference information for proper torque application
Safety First
- Always verify torque specifications with your vehicle's factory service manual
- Use properly calibrated torque wrenches
- Replace all torque-to-yield (TTY) bolts - they are single-use only
- When in doubt, consult a professional mechanic
Quick Reference Guide
Quick Reference Guide
Common Torque Patterns
Star Pattern
Used for wheels and other circular bolt patterns
Cross Pattern
Used for gaskets and cover plates
Sequential Pattern
Used for head bolts and other critical components
Common Mistakes to Avoid
Common Mistakes to Avoid
Over-tightening
Exceeding the specified torque value can stretch or break fasteners, damage threads, or crack components.
Always use a calibrated torque wrench and follow specifications exactly.
Incorrect Torque Sequence
Tightening bolts in the wrong order can cause uneven pressure distribution and potential leaks or damage.
Follow the manufacturer's specified torque sequence pattern.
Dirty Threads
Dirt, rust, or old thread locker can affect torque readings and proper fastener tension.
Clean and inspect all threads before assembly. Use new thread locker if specified.
Reusing TTY Bolts
Torque-to-yield bolts are designed to stretch and must not be reused.
Always replace TTY bolts with new ones. They are single-use only.
Dry vs. Lubricated
Not accounting for whether torque specs are for dry or lubricated fasteners can lead to incorrect tension.
Check if specs are for dry or lubricated threads. Use specified lubricant when required.
Recommended Tools
Recommended Tools
Torque Wrench (1/4" Drive)
Torque Wrench (3/8" Drive)
Torque Wrench (1/2" Drive)
Angle Gauge
Torque Wrench Care
- Calibrate annually or after 5,000 clicks
- Store at lowest setting
- Keep clean and lubricated
Search Specifications
Search by component name, bolt size, or description
Torque Calculator
Convert between different torque units
Oxygen Sensors
This subsystem includes all pre and post-catalyst oxygen sensors, responsible for monitoring the exhaust gas composition and aiding in emissions control. These sensors are threaded into the exhaust manifold or exhaust pipe.
1 Pre-Catalyst Oxygen Sensor (Bank 1 & 2)
M18 x 1.5
Pre-Catalyst Oxygen Sensor (Bank 1 & 2)
M18 x 1.5Torque Value
Important Notes
2 Post-Catalyst Oxygen Sensor (Bank 1 & 2)
M18 x 1.5
Post-Catalyst Oxygen Sensor (Bank 1 & 2)
M18 x 1.5Torque Value
Important Notes
Nox Sensors
This subsystem includes the NOx sensors, which are responsible for monitoring nitrogen oxide levels in the exhaust gas. This system includes the sensor and its control unit.
1 NOx Sensor (Bank 1 & 2)
M12 x 1.75
NOx Sensor (Bank 1 & 2)
M12 x 1.75Torque Value
Important Notes
2 NOx Sensor Control Unit Mounting Bolts
M6 x 1.0
NOx Sensor Control Unit Mounting Bolts
M6 x 1.0Torque Value
Important Notes
Exhaust Gas Temperature Sensors
This subsystem includes the EGT sensors, which monitor the temperature of the exhaust gases at various points in the system.
1 Exhaust Gas Temperature Sensor (EGT) Mounting Bolts (M6)
M6 x 1.0
Exhaust Gas Temperature Sensor (EGT) Mounting Bolts (M6)
M6 x 1.0Torque Value
Important Notes
2 Exhaust Gas Temperature Sensor (EGT) Mounting Bolts (M8)
M8 x 1.25
Exhaust Gas Temperature Sensor (EGT) Mounting Bolts (M8)
M8 x 1.25Torque Value
Important Notes
Exhaust Pressure Sensors
This subsystem includes the exhaust pressure sensors, typically found on the DPF or exhaust manifold, measuring the pressure within the exhaust system.
1 Exhaust Pressure Sensor Mounting Bolts
M6 x 1.0
Exhaust Pressure Sensor Mounting Bolts
M6 x 1.0Torque Value
Important Notes
Wiring Harness Brackets
This subsystem includes all brackets that secure the wiring harnesses for the lambda (O2) sensors and other related components.
1 Lambda Sensor Wiring Harness Bracket Bolts
M6 x 1.0
Lambda Sensor Wiring Harness Bracket Bolts
M6 x 1.0Torque Value
Important Notes
Dpf Sensors
This subsystem includes the differential pressure sensor and related components for the Diesel Particulate Filter (DPF).
1 Differential Pressure Sensor (DPF) Mounting Bolts
M6 x 1.0
Differential Pressure Sensor (DPF) Mounting Bolts
M6 x 1.0Torque Value
Important Notes
Intake Sensors
This subsystem includes sensors that are mounted to the intake manifold or air intake system.
1 Manifold Pressure Sensor Mounting Bolts
M5 x 0.8
Manifold Pressure Sensor Mounting Bolts
M5 x 0.8Torque Value
Important Notes
2 Mass Airflow Sensor (MAF) Mounting Bolts
M5 x 0.8
Mass Airflow Sensor (MAF) Mounting Bolts
M5 x 0.8Torque Value
Important Notes
Evap System
This subsystem includes the components related to the evaporative emission system, such as the purge valve.
1 Evaporative Emission (EVAP) Purge Valve Mounting Bolts
M6 x 1.0
Evaporative Emission (EVAP) Purge Valve Mounting Bolts
M6 x 1.0Torque Value
Important Notes
Troubleshooting Guide
Common issues, diagnostic steps, and prevention guidelines
Common Issues
Bolt stretching, stripped threads, uneven torque patterns
Common Issues
Bolt stretching, stripped threads, uneven torque patterns
Loose Components
Symptoms:
- Rattling or vibration noises
- Visible movement in components
- Uneven panel gaps
Solutions:
- Clean threads and mounting surfaces
- Replace damaged fasteners
- Apply proper torque in sequence
- Use thread locker if specified
Stripped Fasteners
Symptoms:
- Unable to achieve proper torque
- Fastener spins freely
- Visible thread damage
Solutions:
- Use thread repair kit if appropriate
- Install thread insert (HeliCoil)
- Replace component if threaded hole is damaged
- Upgrade to higher grade fastener if recommended
Overtightened Components
Symptoms:
- Cracked or deformed parts
- Broken fasteners
- Compressed gaskets or seals
Solutions:
- Replace damaged components
- Use new fasteners
- Follow proper torque sequence
- Verify correct torque specifications
Diagnostic Steps
Visual inspection, torque verification, thread assessment
Diagnostic Steps
Visual inspection, torque verification, thread assessment
Visual Inspection
Inspect the affected area for any visible signs of damage or wear
- Check for cracks or deformation
- Look for signs of excessive wear
- Verify proper fastener installation
Torque Verification
Verify the torque applied to the fasteners
- Check the torque wrench calibration
- Verify the torque specification
- Compare the applied torque to the specification
Thread Assessment
Assess the condition of the threads
- Check for signs of thread damage
- Verify the thread type and size
- Check for proper thread engagement
Prevention Guidelines
Best practices, maintenance tips, tool care
Prevention Guidelines
Best practices, maintenance tips, tool care
Best Practices
- Always follow the recommended torque specification
- Use the correct type and size of fasteners
- Verify the torque wrench calibration regularly
Maintenance Tips
- Regularly inspect the affected area for signs of wear or damage
- Replace damaged or worn-out components promptly
- Keep the work area clean and organized
Tool Care
- Regularly clean and maintain the torque wrench
- Store the torque wrench in a dry and secure location
- Verify the torque wrench calibration before each use
Frequently Asked Questions
Find answers to common questions about torque specifications
Q1 Why are correct torque specifications important for emissions sensors?
Why are correct torque specifications important for emissions sensors?
Correct torque is crucial to ensure a proper seal and prevent leaks in the emissions system. Under-torquing can lead to exhaust leaks, resulting in incorrect sensor readings and potential damage to the catalytic converter or other components. Over-torquing can damage sensor threads, mounting points, or the sensor itself, leading to expensive repairs or sensor failure. Precise torque ensures sensors are secure without risking damage.
Q2 What happens if I over-tighten an emissions sensor?
What happens if I over-tighten an emissions sensor?
Over-tightening can damage the sensor's threads or the threads in the exhaust system, potentially leading to the sensor breaking or becoming difficult to remove. You might also crush the sealing washer, which can cause leaks. In some cases, the internal components of the sensor can be damaged, leading to inaccurate readings or sensor failure requiring replacement and potentially a re-thread operation on the mounting point.
Q3 What happens if I under-tighten an emissions sensor?
What happens if I under-tighten an emissions sensor?
Under-tightening can cause exhaust leaks, which can trigger the check engine light and affect engine performance. These leaks can also introduce incorrect readings to the oxygen and NOx sensors, leading to further issues. In addition to this, unseated emissions sensors may vibrate loose and cause more extensive damage.
Q4 Should I use thread locker on emissions sensor bolts?
Should I use thread locker on emissions sensor bolts?
It's generally not recommended to use thread locker on emissions sensor bolts unless specifically instructed by the manufacturer or service manual. Some sensors rely on electrical grounding through the threads, and thread locker can interfere with this connection. Typically, using the correct torque and a new sealing washer is sufficient for a secure and leak-free installation. Always refer to the manufacturer's instructions.
Q5 Do I need a special tool to torque emissions sensor bolts?
Do I need a special tool to torque emissions sensor bolts?
While a standard torque wrench will generally suffice, for some sensors, a crowsfoot wrench or a specialized sensor socket may be needed to access the bolt without obstruction. This is particularly true for sensors located in tight spaces within the exhaust system. Using the correct tool will help ensure accurate torque and prevent damage to the sensor or surrounding components.
Environmental Considerations
Temperature, humidity, and seasonal effects on torque specifications
Temperature Effects
Includes: High Heat, Cold Weather, Thermal Cycling
Temperature Effects
Includes: High Heat, Cold Weather, Thermal Cycling
Temperature can significantly impact torque values and fastener behavior
Cold Weather
Effects:
- Increased material brittleness
- Higher torque required due to thread contraction
- Reduced thread lubricant effectiveness
Recommendations:
- Allow components to warm to room temperature when possible
- Consider using winter-grade thread lubricants
- Check torque values more frequently during winter months
Hot Weather
Effects:
- Thermal expansion of components
- Decreased friction in threads
- Accelerated lubricant breakdown
Recommendations:
- Check torque when components are at normal operating temperature
- Use temperature-resistant thread lockers
- Consider re-torquing after heat cycles
Humidity and Corrosion
Covers: Rust Prevention, Salt Exposure, Moisture Control
Humidity and Corrosion
Covers: Rust Prevention, Salt Exposure, Moisture Control
Moisture and corrosion can affect fastener integrity and torque values
High Humidity
Effects:
- Accelerated corrosion formation
- Reduced friction coefficient
- Potential thread seizing
Prevention:
- Use corrosion-resistant fasteners
- Apply appropriate anti-seize compounds
- Maintain proper protective coatings
Salt Exposure
Effects:
- Rapid corrosion development
- Thread damage
- Seized fasteners
Prevention:
- Regular underbody washing
- Use of sacrificial anodes where appropriate
- Application of protective coatings
Seasonal Maintenance
Spring, Summer, Fall, and Winter maintenance schedules
Seasonal Maintenance
Spring, Summer, Fall, and Winter maintenance schedules
Spring
- Inspect for winter damage
- Clean and protect exposed fasteners
- Check torque on critical components
Summer
- Monitor heat-affected components
- Check expansion-related loosening
- Inspect cooling system mounts
Fall
- Prepare for winter conditions
- Apply corrosion protection
- Verify all fasteners are properly torqued
Winter
- More frequent inspection of critical fasteners
- Check for salt damage
- Monitor suspension component torque
Related Resources
Tools, service procedures, and technical bulletins
Recommended Tools
Torque Wrench (1/4" Drive)
A calibrated torque wrench is essential for accurately tightening sensor bolts to the manufacturer's specifications.
- Accuracy within +/- 3%
- Range of 5-25 Nm
- Click type indicator
Torx Socket Set
A set of Torx sockets, specifically T25, T27 and T30, is needed to access and tighten the bolts securing the emissions sensors.
- Sizes T25, T27, T30
- Durable construction
- Variety of drive sizes
Ratchet (1/4" Drive)
A ratchet handle is needed to rotate the torque wrench with the attached torx sockets
- Fine tooth gear
- Quick release mechanism
- Comfort grip handle
Service Procedures
Oxygen Sensor Replacement
Procedure for removing and installing an oxygen sensor, including proper torque specifications.
- Disconnect the negative battery terminal.
- Locate the affected oxygen sensor.
- Disconnect the electrical connector from the sensor.
- Using the appropriate Torx socket, carefully remove the old sensor.
- Install the new sensor, ensuring the threads are clean and the sensor is properly seated.
- Torque the sensor mounting bolts to the specified torque of 10 Nm (89 in-lbs).
- Reconnect the electrical connector.
- Reconnect the negative battery terminal.
- Verify proper operation with diagnostic tool.
NOx Sensor Replacement
Procedure for removing and installing an NOx sensor, including proper torque specifications.
- Disconnect the negative battery terminal.
- Locate the affected NOx sensor.
- Disconnect the electrical connector from the sensor.
- Using the appropriate Torx socket, carefully remove the old sensor.
- Install the new sensor, ensuring the threads are clean and the sensor is properly seated.
- Torque the sensor mounting bolts to the specified torque of 8 Nm (71 in-lbs).
- Reconnect the electrical connector.
- Reconnect the negative battery terminal.
- Verify proper operation with diagnostic tool.
Exhaust Gas Temperature (EGT) Sensor Replacement
Procedure for removing and installing an EGT sensor, including proper torque specifications.
- Disconnect the negative battery terminal.
- Locate the affected EGT sensor.
- Disconnect the electrical connector from the sensor.
- Using the appropriate Torx socket, carefully remove the old sensor.
- Install the new sensor, ensuring the threads are clean and the sensor is properly seated.
- Torque the sensor mounting bolts to the specified torque of 8 Nm (71 in-lbs).
- Reconnect the electrical connector.
- Reconnect the negative battery terminal.
- Verify proper operation with diagnostic tool.
Technical Service Bulletins
Torque Specification Update for Emissions Sensors
2020-05-15A revised torque specification is now in place for all emissions-related sensors on certain Audi models. Failure to adhere to this specification may result in sensor malfunction or damage.
Resolution: Always refer to the latest service manual or technical documentation for the most current torque specifications. For Oxygen and EGT sensors torque to 10 Nm (89 in-lbs). For NOx sensors torque to 8 Nm (71 in-lbs).
Potential Cross Threading Issues with NOx Sensors
2021-09-01Reports have indicated potential cross threading of NOx sensor mounting threads during installation. Precautions should be taken during the removal and installation of NOx sensors.
Resolution: Ensure threads are clean and not damaged before installing. Start threads by hand before tightening to the required torque of 8 Nm (71 in-lbs). Do not force the sensor.
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Technical Information
- All specifications, including torque values, fluid capacities, and maintenance procedures, should be verified against your vehicle's factory service manual.
- Vehicle specifications and procedures may vary by model year, trim level, and region.
- Always follow the manufacturer's recommended procedures and safety precautions.
- Working on vehicles can be dangerous. Always take proper safety precautions and use appropriate safety equipment.
- If you're unsure about any procedure, consult a qualified professional mechanic.