BMW 335i 2005-2011 Emissions & Sensor Bolt Torque Specifications
Detailed torque specifications for all emission sensors on the 2005-2011 BMW 335i (E90, E92, E93) chassis. Includes oxygen sensors, pressure sensors, and temperature 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
Exhaust System
Torque specifications for bolts related to the exhaust system, including the manifold, catalytic converter, and oxygen sensors. These components are critical for proper emissions control and sensor accuracy.
1 Exhaust Manifold/Headers to Cylinder Head Bolts
M8 x 1.25
Exhaust Manifold/Headers to Cylinder Head Bolts
M8 x 1.25Torque Value
Important Notes
2 Exhaust Manifold/Headers Bolts
M8 x 1.25
Exhaust Manifold/Headers Bolts
M8 x 1.25Torque Value
Important Notes
3 Catalytic Converter to Exhaust Pipe Bolts
M10 x 1.5
Catalytic Converter to Exhaust Pipe Bolts
M10 x 1.5Torque Value
Important Notes
4 Upstream Oxygen (O2) Sensor
M18 x 1.5
Upstream Oxygen (O2) Sensor
M18 x 1.5Torque Value
Important Notes
5 Downstream Oxygen (O2) Sensor
M18 x 1.5
Downstream Oxygen (O2) Sensor
M18 x 1.5Torque Value
Important Notes
Intake System
Torque specifications for bolts related to the intake system, including the throttle body, intake manifold, and associated sensors. Proper torque is crucial for preventing vacuum leaks and ensuring accurate sensor readings.
1 Throttle Body Bolts
M6 x 1.0
Throttle Body Bolts
M6 x 1.0Torque Value
Important Notes
2 Intake Manifold Bolts
M8 x 1.25
Intake Manifold Bolts
M8 x 1.25Torque Value
Important Notes
3 Mass Air Flow (MAF) Sensor Bolts
M5 x 0.8
Mass Air Flow (MAF) Sensor Bolts
M5 x 0.8Torque Value
Important Notes
4 Manifold Absolute Pressure (MAP) Sensor Bolt
M5 x 0.8
Manifold Absolute Pressure (MAP) Sensor Bolt
M5 x 0.8Torque Value
Important Notes
5 Intake Air Temperature (IAT) Sensor
M6 x 1.0
Intake Air Temperature (IAT) Sensor
M6 x 1.0Torque Value
Important Notes
Egr System
Torque specifications for bolts securing the EGR valve. Proper torque is critical for preventing leaks and ensuring the EGR valve operates correctly.
1 EGR Valve Bolts
M8 x 1.25
EGR Valve Bolts
M8 x 1.25Torque 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 is using the correct torque specifications important for emissions sensors?
Why is using the correct torque specifications important for emissions sensors?
Using the correct torque specifications is critical to ensure a proper seal and function of the emissions sensors. Over-tightening can damage the sensor threads, housing, or mounting point, leading to leaks, inaccurate readings, or sensor failure. Under-tightening can result in exhaust leaks and false readings, triggering check engine lights. For example, an over-torqued oxygen sensor can crack its ceramic element, rendering it useless, while an under-torqued one may allow exhaust to escape, falsely indicating a lean condition. Proper torque also prevents loosening due to vibrations.
Q2 What tools are recommended for torquing emissions sensor bolts?
What tools are recommended for torquing emissions sensor bolts?
A torque wrench is essential for accurate torque application. Avoid using standard wrenches or impact guns for final tightening, as they can easily overtighten bolts. For emissions sensors, specifically O2 sensors, an oxygen sensor socket (typically a slotted socket allowing wire passage) is also highly recommended. Using the correct tools ensures that the bolts are tightened to the correct torque and prevents damage to the sensors.
Q3 Do I need to use thread sealant or anti-seize on emissions sensor threads?
Do I need to use thread sealant or anti-seize on emissions sensor threads?
Yes, it's generally recommended to use anti-seize on the threads of emissions sensors, especially oxygen sensors. This prevents the threads from seizing or corroding over time, making future removal easier. Some new sensors come pre-coated with anti-seize. However, ensure the anti-seize used is sensor-safe, as some can interfere with sensor readings. Avoid any thread sealant which could interfere with electrical conductivity in grounded sensors. Always refer to your vehicle's repair manual for specific recommendations.
Q4 Can I reuse the bolts for emissions sensors?
Can I reuse the bolts for emissions sensors?
While you can technically reuse some bolts, it's generally recommended to replace any bolts that look corroded or damaged when removing emissions sensors. Especially if the original torque specification requires the use of torque-to-yield bolts, which are designed for one-time use, these should never be reused. The small cost of new bolts is often worth it to ensure proper sealing and prevent future problems. Bolts that have stretched after being over-torqued may not hold the sensor correctly.
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
A calibrated torque wrench is essential for applying the correct torque to emissions sensor bolts.
- Adjustable torque settings
- Accurate torque application
Socket Set (Metric)
A set of metric sockets is needed to fit the various bolt heads on the emissions sensors.
- Variety of socket sizes
- Durable construction
Extension Bars
Extension bars may be required to reach some emissions sensors.
- Various lengths available
- Provides access to hard-to-reach areas
Service Procedures
Oxygen Sensor Replacement (Pre-Cat)
Procedure for removing and installing the pre-catalytic converter oxygen sensors, including torque specifications.
- Disconnect the negative battery terminal.
- Locate the pre-cat oxygen sensor on the exhaust manifold.
- Disconnect the electrical connector to the sensor.
- Use a wrench or oxygen sensor socket to remove the old sensor.
- Install the new sensor by hand, then tighten with a torque wrench to 30 Nm.
- Reconnect the electrical connector and battery terminal.
Oxygen Sensor Replacement (Post-Cat)
Procedure for removing and installing the post-catalytic converter oxygen sensors, including torque specifications.
- Disconnect the negative battery terminal.
- Locate the post-cat oxygen sensor on the exhaust after the catalytic converter.
- Disconnect the electrical connector to the sensor.
- Use a wrench or oxygen sensor socket to remove the old sensor.
- Install the new sensor by hand, then tighten with a torque wrench to 30 Nm.
- Reconnect the electrical connector and battery terminal.
NOx Sensor Replacement
Procedure for removing and installing the NOx sensor, including torque specifications.
- Disconnect the negative battery terminal.
- Locate the NOx sensor on the exhaust system.
- Disconnect the electrical connector to the sensor.
- Use a wrench or socket to remove the mounting bolts.
- Install the new sensor by hand, then tighten the bolts with a torque wrench to 20 Nm.
- Reconnect the electrical connector and battery terminal.
Exhaust Gas Temperature Sensor Replacement
Procedure for removing and installing the Exhaust Gas Temperature (EGT) sensors, including torque specifications.
- Disconnect the negative battery terminal.
- Locate the EGT sensor(s) on the exhaust system.
- Disconnect the electrical connector to the sensor.
- Use a wrench or socket to remove the mounting bolts.
- Install the new sensor by hand, then tighten the bolts with a torque wrench to 20 Nm.
- Reconnect the electrical connector and battery terminal.
Technical Service Bulletins
Excessive NOx Sensor Failures
2008-05-15Technical bulletin regarding high failure rates of NOx sensors due to electrical connector corrosion or internal sensor failure.
Resolution: Replace the NOx sensor, and inspect electrical connector for corrosion. Apply dielectric grease as necessary to prevent future issues.
Incorrect Oxygen Sensor Readings and MIL illumination
2009-11-20Technical bulletin regarding misinterpreting oxygen sensor data due to poor installation or failed heating elements. This often results in the check engine light illuminating.
Resolution: Verify correct sensor installation, inspect the oxygen sensor heater circuits, and replace any faulty parts. Torque oxygen sensors to 30 Nm.
EGT sensor failures due to excessive heat and vibration
2010-03-01Technical bulletin regarding EGT sensor failures caused by heat damage and or vibration damage near the exhaust system
Resolution: Replace the sensor, check the routing of the sensor wiring to avoid excess heat and vibration. Torque EGT sensors to 20 Nm
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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.