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Your vehicle has failed a warrant of fitness because of a noisy exhaust

Published: 11 2009

This pamphlet is written for vehicle owners whose vehicles have failed a WoF because of a noisy exhaust. It contains information on options for fixing the exhaust noise so that the vehicle can pass its WoF.

Noisy vehicle

Your vehicle has failed a warrant of fitness because of a noisy exhaust

Why is checking the exhaust noise part of the WoF inspection?

When your vehicle was manufactured it was fitted with an effective exhaust system, including a silencer. Exhaust gases produce a significant amount of noise. Silencers, as well as any catalytic converters, muffle this noise to an acceptable level. Governments specify the maximum noise levels that vehicles must not exceed when they are manufactured.

When the original exhaust system is modified, replaced or repaired, its effectiveness may be compromised, making the exhaust system louder than the one originally fitted by the vehicle manufacturer. A warrant of fitness (WoF) inspection ensures that the vehicle’s exhaust system is checked regularly for noise output and meets the legal noise requirements.

What are the legal noise requirements?

As a result of public complaints about the number of noisy modified vehicles on the road, the government has introduced more stringent requirements relating to exhaust noise. A vehicle will comply if the noise output from the exhaust system is similar to or less than the noise output from the exhaust system that was originally fitted when the vehicle was manufactured.

The exhaust system may be noisier than the original one provided that:

  • the noise output either remains well below the legal noise limits, or
  • an objective noise test proves that the exhaust system does not exceed the legal noise limits.

From 1 December 2009, if your vehicle is ordered off the road (pink or green stickered) by an enforcement officer for non-compliant exhaust noise, you are required to have your vehicle certified by a low volume vehicle (LVV) certifier as having passed an objective noise test before a new WoF can be issued. Your vehicle is required to pass a new objective noise test every time it is ordered off the road for non-compliant exhaust noise.

What is the objective noise test?

The objective noise test is a stationary tail-pipe noise test procedure based on international standards and can only be carried out by an approved LVV certifier. If your vehicle passes the objective noise test, the LVV certifier will attach a label to the vehicle and issue a certificate. The cost of the test is about $200, depending on location. It is a one-off cost if the vehicle passes the test first time, and provided the exhaust system is maintained in good condition and is not modified further.

How is exhaust noise checked during the WoF inspection?

The WoF inspector uses their experience to assess the noise output of the vehicle compared to other identical or similar vehicles in original and good condition. If your vehicle is noisier than it was originally, it will fail its WoF unless the noise output is well below the legal noise limits. The WoF inspector will assess this using their experience or, if a hand-held noise meter is available, by carrying out a noise quick check.

The noise quick check procedure is a simpler and quicker version of the objective noise test suitable for WoF, and can only be carried out by a WoF inspector. A fee may be charged for this check.

If your vehicle has failed its WoF because of a noisy exhaust, it may be referred to undergo an objective noise test.

What do I need to do to pass the WoF?

You must either:

  • replace, remodify or repair the exhaust system so that the noise output is less than or similar to the noise output of the exhaust system that was originally fitted by the vehicle manufacturer, or
  • undergo an objective noise test if you wish to have an exhaust system that is noisier than the original exhaust. However, you may still need to replace, remodify or repair the exhaust system to bring it below the legal noise limits. An objective noise test is not required if the vehicle can pass the noise quick check.

If your vehicle has been pink or green stickered by an enforcement officer for non-compliant exhaust noise, it must pass an objective noise test. The WoF inspector will need to sight the ordering off the road notice before a WoF can be issued.

Should my vehicle get an objective noise test even though it has passed the noise quick check?

If your vehicle’s exhaust is louder than its original exhaust system, especially if the noise output is close to the permitted noise limit, then it is recommended that you have an objective noise test carried out. By having the label and certificate, you may avoid the inconvenience and cost of:

  • failing a WoF or having to go through a noise quick check at every WoF inspection, or
  • receiving a pink or green sticker.

What are the legal noise limits?

The following table lists the legal noise limits for different vehicle types. In order to pass an objective noise test, the vehicle must not exceed these limits.

Vehicle type Maximun
noise level
(dBA)
Motorcycle or trike with an engine capacity of 125 cc or less 96
Motorcycle or trike with an engine capacity of more than 125 cc 100
Light goods or passenger vehicle (eg, car, MPV, minibus, ute or van)
  • First registered in NZ before 1 June 2008
  • First registered in NZ on or after 1 June 2008, and:

    • - manufactured before 1 January 1985
    • - manufactured on or after 1 January 1985

 

95


 


95


90

What if I disagree with the decision?

If you disagree with the decision to fail your vehicle, you should first try to resolve the issue with the inspecting organisation or the LVV certifier concerned. If you are still not satisfied, you may raise a complaint with the NZ Transport Agency, phone 0800 699 000 or visit www.nzta.govt.nz and download a complaint form.

Where can I get more information?

A list of approved LVV certifiers can be viewed on the Low Volume Vehicle Technical Association website: www.lvvta.org.nz

For more information about the law changes, refer to www.nzta.govt.nz.

Page updated: 1 Dec 2009