2004 Vauxhall Monaro — MOT failures & pass rate
552 MOT tests on the 2004 Vauxhall Monaro are in this dataset, and 83.7% of them passed. That is 11.4 percentage points better than all cars of a similar age, which fail at 27.7%. Failures cluster in brakes, lighting & signalling and emissions & environmental.
What the MOT record shows
No single area dominates — brakes (7.4%) and lighting & signalling (6.7%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are rigid brake pipes, catalyst emissions and rbt (sp) — rigid brake pipes alone was recorded 28 times.
Condition tracks the odometer closely. Failures run at 13.5% in the 30-60k band and 28.2% in the 120-150k band, a 14.8-point spread — more than double.
Advisories point at the next bill rather than this one: brakes was flagged on 33.1% of tests without failing them.
The trend is improving — the fail rate fell from 17.9% in 2021 to 13.0% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Brakes | 7.4% | 41 |
| 2 | Lighting & signalling | 6.7% | 37 |
| 3 | Emissions & environmental | 5.1% | 28 |
| 4 | Suspension | 4.9% | 27 |
| 5 | Steering | 2.9% | 16 |
| 6 | Body, structure & corrosion | 2.5% | 14 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Rigid brake pipes | 28 |
| 2 | Catalyst emissions | 20 |
| 3 | Rbt (sp) | 14 |
| 4 | Side repeaters | 13 |
| 5 | Wipers | 11 |
| 6 | Headlamp aim | 10 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Brakes | 33.1% | 183 |
| 2 | Suspension | 19.2% | 106 |
| 3 | Tyres | 18.5% | 102 |
| 4 | Body, structure & corrosion | 10.1% | 56 |
| 5 | Steering | 9.2% | 51 |
| 6 | Other defects | 9.1% | 50 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 30-60k | 119 | 13.5% |
| 60-90k | 211 | 14.2% |
| 90-120k | 134 | 16.4% |
| 120-150k | 39 | 28.2% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 123 | 17.9% |
| 2022 | 114 | 17.5% |
| 2023 | 107 | 14.0% |
| 2024 | 108 | 18.5% |
| 2025 | 100 | 13.0% |
What to check before buying a 2004 Monaro
On a 2004 Monaro, brakes is what the MOT record says goes wrong most — it appeared in 7.4% of tests. Check these areas before you commit.
- Brakes (7.4% of tests): Pads/discs are routine wear; binding, imbalance or corroded pipes are more serious — test for pulling under braking. Typical repair: £100–£350 per axle.
- Lighting & signalling (6.7% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Emissions & environmental (5.1% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
How many 2004 Vauxhall Monaros pass their MOT?
83.7% of the 552 2004 Vauxhall Monaro MOT tests in this dataset passed — a 16.3% fail rate.
What is the most common MOT failure on a 2004 Vauxhall Monaro?
Brakes, recorded in 7.4% of tests, followed by lighting & signalling (6.7%).
Does the 2004 Monaro get worse with mileage?
Its MOT fail rate rises from 13.5% in the 30-60k band to 28.2% in the 120-150k band.
Methodology & source. Based on 552 MOT tests. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-27. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.