Failure category
Exhaust & emissions
Exhaust splits, mounts, catalytic converters, transmission CV-joint boots, emissions-related faults.
Defect codes
21
Total fails
1,020,441
Defect codes in this category, ranked.
Sorted by total cars affected last year. Click any row for the full defect description plus the models most at risk.
- 01 535,592
A transmission shaft constant velocity joint boot severely deteriorated
542 models affected
- 02 393,304
A transmission shaft constant velocity joint boot missing or no longer prevents the ingress of dirt etc
362 models affected
- 03 63,788
Exhaust system leaking or insecure
146 models affected
- 04 15,473
Exhaust system leaking or insecure
17 models affected
- 05 8,527
Emissions levels exceed the manufacturer's specified limits
63 models affected
- 06 1,328
Emissions levels exceed default limits
36 models affected
- 07 931
Emissions levels exceed default limits
23 models affected
- 08 429
Exhaust system leaking or insecure
43 models affected
- 09 338
Exhaust noise levels in excess of those permitted
40 models affected
- 10 314
Emissions levels exceed default limits
16 models affected
- 11 140
Emissions test unable to be completed
11 models affected
- 12 98
Emissions levels exceed the manufacturer's specified limits
7 models affected
- 13 43
Emissions levels exceed default limits
2 models affected
- 14 32
Emissions levels exceed default limits
5 models affected
- 15 28
Emissions levels exceed default limits
5 models affected
- 16 23
An exhaust silencer marked ‘NOT FOR ROAD USE’, ‘TRACK USE ONLY’ or similar words
7 models affected
- 17 22
A transmission shaft bearing excessively worn
1 models affected
- 18 17
Emissions test unable to be completed
2 models affected
- 19 6
An induction or exhaust leak that could affect emissions levels
1 models affected
- 20 5
Exhaust system leaking or insecure
2 models affected
- 21 3
Emissions test unable to be completed
1 models affected
Brands most affected.
Total category-fails across each manufacturer's tested fleet. High-volume brands naturally lead — read alongside their model pass-rates.