Common problems

Porsche 911 common problems

What MOT testers find on the Porsche 911: the parts that fail or get advisories most often at each age, against all cars of the same age. From 174,386 DVSA MOT tests taken 2022 to 2025.

MOT data updated 28 September 2026

At 19 years, the most tested age

Lights and electrics fails per 100 MOTs (n=10,748)6.3

All cars at 19 years (n=2,479,858)21.5

Brakes advisories and minor defects per 100 MOTs (n=10,748)19.4

All cars, same age (n=2,479,858)33.3

What stands out

No part area of the Porsche 911 fails more than 1 point per 100 MOTs above all cars at 19 years old (n=10,748; all cars n=2,479,858).
Lights and electrics fails are less common: 6.3 per 100 MOTs against 21.5 for all cars at the same age.
The fail item testers record most often at 19 years: catalyst emissions: Lambda reading after 2nd fast idle outside specified limits, on 2.5 per 100 MOTs (all cars 1.4).
The most common advisory or minor defect: rigid brake pipes: corroded, covered in grease or other material, on 11.5 per 100 MOTs.

Problems by part at 19 years

How many of every 100 MOTs found a fail, or an advisory or minor defect, in each area. A test with faults in two areas counts in both.

Porsche 911 at 19 years (n=10,748) against all cars at 19 years (n=2,479,858). Per 100 MOTs.
Area	Fails	All cars	Advisories	All cars
Lights and electrics	6.3	21.5	5.3	17.9
Exhaust, emissions and leaks	3.6	7.0	4.9	14.7
Brakes	3.2	13.3	19.4	33.3
Tyres	2.8	6.8	14.5	26.9
Body and structure	2.4	9.0	3.8	15.2
Suspension	1.8	16.9	8.1	35.4
Windscreen, wipers and mirrors	1.6	7.5	2.7	6.3
Steering	0.7	4.1	1.8	6.0
Number plates and VIN	0.6	0.7	0.8	5.9
Seat belts and airbags	0.4	2.9	0.4	1.4
Road wheels	0.1	0.5	0.3	1.2

What testers fail most on the 911 at 19 years

Fail items on the Porsche 911 at 19 years (n=10,748), per 100 MOTs, with all cars at the same age (n=2,479,858).
Item	Area	Per 100 MOTs	All cars	Typical repair (estimate)
Catalyst emissions: Lambda reading after 2nd fast idle outside specified limits	Exhaust, emissions and leaks	2.5	1.4
Side/position light not working	Lights and electrics	1.7	5.4	£10 to £47 per lamp
Rigid brake pipes: excessively corroded	Brakes	1.5	2.5	£137 to £392 per car (rough guide)
Headlight aimed too high	Lights and electrics	1.3	1.2	£16 to £39 per car (rough guide)
Driveshaft CV boot split	Body and structure	1.3	3.2	£88 to £196 per boot (rough guide)
Tyre with cords exposed	Tyres	0.9	1.6	£88 to £145 per tyre
Tyre tread below 1.6 mm	Tyres	0.9	2.8	£88 to £145 per tyre
Wipers not clearing screen	Windscreen, wipers and mirrors	0.8	3.3	£15 to £30 per blade
Headlamp aim: too low	Lights and electrics	0.7	1.7	£16 to £39 per car (rough guide)
Exhaust system: has a major leak of exhaust gases	Body and structure	0.7	2.1	£182 to £263 per section

Early warnings: advisories and minor defects at 19 years

Advisories and minor defects are recorded, but the car still passes. Across all cars, a part with an advisory or minor defect failed at the next MOT 5.5 times in 100 (n=88,666,940 pairs of consecutive MOTs), against 0.3 times in 100 when the same part had none (n=12,936,860,350).

Advisories and minor defects on the Porsche 911 at 19 years (n=10,748), per 100 MOTs, with all cars at the same age (n=2,479,858).
Item	Area	Per 100 MOTs	All cars	If it needs replacing (estimate)
Rigid brake pipes: corroded, covered in grease or other material	Brakes	11.5	14.1	£137 to £392 per car (rough guide)
Tread depth: worn close to legal limit/worn on edge	Tyres	9.1	16.6	£88 to £145 per tyre
Brake discs: worn, pitted or scored, but not seriously weakened	Brakes	8.7	10.8	£148 to £376 per axle (rough guide)
Tyre condition: slightly damaged/cracking or perishing	Tyres	4.8	9.9	£88 to £145 per tyre
Engine oil leaks: leak, but not excessive	Exhaust, emissions and leaks	4.2	13.2
Exhaust system: has a minor leak of exhaust gases	Body and structure	2.1	5.3	£182 to £263 per section
Windscreen: damaged but not adversely affecting driver's view	Windscreen, wipers and mirrors	2.1	3.8
Play in steering rack inner joint(s)	Other	1.9	3.7
Registration plate lamp(s): inoperative in the case of multiple lamps or light sources	Lights and electrics	1.8	5.6
Suspension arm pins and bushes: pin or bush worn but not resulting in excessive movement	Suspension	1.5	8.1	£92 to £237 per arm (rough guide)

Repair estimates are a guide for an independent garage: labour at the national median local garage rate (median £78 an hour from 65 garages, ONS price quotes) times estimated labour hours, plus a parts band. Labour hours and most parts bands are estimates, not quotes, and prices vary by model, engine and region. A warning light fault shows the cost of the diagnosis only.

How problems change with age

Fails per 100 MOTs in the three most common areas at 19 years. Ages with fewer than 1,000 tests are not shown.
Age	Tests (n)	Lights and electrics	Exhaust, emissions and leaks	Brakes
3 years	8,273	0.8	0.1	0.1
4 years	8,028	0.6	0.3	0.1
5 years	8,072	0.9	0.2	0.2
6 years	8,228	0.9	0.2	0.3
7 years	7,582	1.1	0.3	0.4
8 years	6,995	1.1	0.2	0.4
9 years	6,387	1.2	0.6	0.3
10 years	6,228	1.4	0.5	0.5
11 years	5,750	1.6	0.6	0.7
12 years	5,890	1.9	0.7	0.8
13 years	6,120	2.4	0.8	0.9
14 years	6,470	3.3	1.2	1.2
15 years	7,697	3.6	1.3	1.4
16 years	8,838	3.7	2.3	2.0
17 years	10,117	4.2	3.1	2.1
18 years	10,680	5.1	3.1	2.5
19 years	10,748	6.3	3.6	3.2
20 years	10,420	7.7	3.8	3.8
21 years	9,171	8.7	3.7	3.7
22 years	7,606	9.8	3.7	4.1
23 years	6,184	9.9	4.0	4.0
24 years	4,896	9.3	3.0	5.1
25 years	4,006	9.7	3.5	4.2

Mileage

At 19 years, Porsche 911 cars showing 30,000 to 60,000 miles failed 10.5% of MOTs (n=3,012); the band that failed most, 90,000 to 120,000 miles, failed 22.9% (n=2,047). For pass and fail rates by age, see Porsche 911 MOT fail rates.

What to check on a viewing

On the Porsche 911, testers most often record catalyst emissions: Lambda reading after 2nd fast idle outside specified limits; side/position light not working; rigid brake pipes: excessively corroded. Look at these first, then the areas below.

Lights and electrics

With someone outside, try every light: dipped and main beam, indicators, brake lights, fog lights and number plate lamps.
Check that the warning lights come on with the ignition and go out once the engine runs.
Look for misted, cracked or yellowed headlamp lenses.

Exhaust, emissions and leaks

Start the engine from cold if you can and watch the exhaust for blue or black smoke.
Check that the engine warning light goes out after starting and stays out on the test drive.
Look under the car and around the engine for oil or fluid leaks, and listen for a blowing exhaust.

Brakes

On the test drive the car should stop in a straight line without pulling, juddering or grinding.
Look at the discs through the wheels for a deep lip, heavy rust or scoring.
Check that the handbrake or electronic parking brake holds the car on a slope.
Ask when the pads, discs and brake fluid were last changed, and for the receipts.

Ask for the car's MOT history and service record: advisories that repeat from one year to the next show what has been left. GOV.UK MOT history.

Questions

What are the most common problems on the Porsche 911?

At 19 years, the age with the most MOT tests (10,748), the fail items testers record most often on the Porsche 911 are catalyst emissions: Lambda reading after 2nd fast idle outside specified limits (2.5 per 100 MOTs), side/position light not working (1.7 per 100 MOTs), rigid brake pipes: excessively corroded (1.5 per 100 MOTs). The most common advisories or minor defects are rigid brake pipes: corroded, covered in grease or other material (11.5) and tread depth: worn close to legal limit/worn on edge (9.1).

Which parts of the Porsche 911 fail more often than on other cars?

None by more than 1 point per 100 MOTs at 19 years, compared with 2,479,858 MOTs of all cars the same age.

Porsche 911 problems by area

Other Porsche models

All Porsche models · Common problems by make

Read this with care. A fail rate is not a measure of build quality. How far cars are driven, how they are used and how well owners maintain them all change it, and wear items such as tyres and brake pads are common fails. Compare a model only with cars of the same age. Methodology and limits.

The all cars figures cover all class 4 vehicles (cars and light vans) tested at the same age.

Looking at a Porsche 911?

These figures describe the model, not the car in front of you. Found one you might buy? See what the VetTheCar Buying Report covers, or use the tools that work without a registration.

See a sample report Car tools · MOT fail rates by model · Compare models by MOT record

Repair estimates: ONS consumer price quotes for local garage labour (09/2025 to 08/2026), the MOT inspection manual for defect wording, and estimated labour hours and parts bands. Not affiliated with or endorsed by ONS.

Source

Contains public sector information licensed under the Open Government Licence v3.0. Source: DVSA anonymised MOT test data, class 4 normal MOT tests, 2022 to 2025. MOT data updated 28 September 2026.

Not affiliated with or endorsed by DVSA. How we calculate these figures · Data sources