Misfire or rough idle on the 2003 Audi A4
When misfire or rough idle gets reported
Owners of the 2003 Audi A4 report misfire or rough idle at a median of 75,000 miles. A quarter of the reports come in before 30,000 miles and a quarter after 90,000 miles, from 17 reports that carried an odometer reading.
A part like this is normally expected to survive 92,000 miles. It is the 2nd most-reported problem on this model year.
The mileage distribution
The reported range runs from 20,000 miles at the tenth percentile to 110,000 miles at the ninetieth, a spread of 90,345 miles across the middle 80% of reports.
A spread this wide points at use rather than design. Towing, climate, service history and city mileage all move a failure like this, so the median is a weak guide to any individual car.
29% of the dated reports were filed under 36,000 miles.
The whole distribution
| 10th | 25th | Median | 75th | 90th |
|---|---|---|---|---|
| 22,000 miles | 32,000 miles | 74,886 miles | 90,053 miles | 112,345 miles |
Read the 10th percentile as “one report in ten arrived this early”. Exact figures are shown in this table because it is the table of record; everywhere else on the site they are rounded to the precision the sample can carry.
What a percentile can and cannot tell you here
These five numbers describe the readings owners gave, in order. The median is the middle one: half the reports arrived below it. The 10th and 90th are the edges of the bulk of the distribution, and the distance between them is the part worth reading. A tight spread — say 70,000 to 95,000 miles — points at something that wears out on a schedule, and the schedule is knowable. A wide one, 20,000 to 190,000, points at a fault that hits some cars and never troubles others, which means the mileage on the listing in front of you tells you very little about your odds.
What these figures are not is a survival curve. Every reading here comes from a car whose owner filed a complaint, so the sample contains only failures: it cannot say what share of the fleet made it past 150,000 miles untouched, because those owners had nothing to report. Nor is the mileage the moment of failure — it is the odometer reading as recalled at the time of filing, which may be weeks later and is sometimes rounded to the nearest ten thousand by the person typing it.
Percentiles are shown at all only once 8 readings exist for the vehicle and mode. Below that the middle of a handful of numbers is noise wearing a decimal point, so the figures are withheld rather than dressed up.
What happens, and what it costs
Putting it right typically runs $250–$1,600 at an independent US shop. That range is an editorial estimate held in this site's failure-mode catalogue, not a figure from NHTSA, and it is a repair cost rather than a diagnosis cost.
The same failure on other years
The same failure is reported on 6 model years of this car. It shows up earliest on the 2002, at a median of 10,000 miles, and latest on the 1998 at 110,000 miles.
By volume the 2002 carries the most reports, with 48; the 2003 has 17. A mode that appears across most years of a model is usually a design choice rather than a bad batch.
If one year stands out to the left, that is the year to avoid; if the whole line sits at a similar mileage, this is wear rather than a defect in one production run.
Tick median reported mileage Solid middle half of reports Faint 10th to 90th percentile Colour how bad the failure is when it happens
What owners wrote
Verbatim from NHTSA complaint narratives, trimmed for length. The mileage is the one the owner gave.
In 1/04, during normal driving conditions one evening, my '03 1.8t a4 began shaking violently as I began accelerated from a stop sign. The check engine light came on and I lost a significant amount of power and couldn't accelerate well. The dealer stated that I blew an ignition coil. Not 2 months later, in early 3/04, the same exact situation occured and I had to have another ignition coil replaced. I have learned that the mfr had a product recall for this exact problem, however my vehicle's components are not covered by those under recall. I was told I have the "newer" versions of the igition coils already in my car. While they might be newer, they sure haven't solved the underlying problem! Two blown igition coils in less than 2 months and I can't get the mfr to replace the other 2 coils that I'm certain will go out at some point soon too.
Dt: the contact states while driving at 10-15 MPH the engine began to stall, followed by the check engine light. There had been no prior incidents. The vehicle would not accelerate beyond 20 MPH. There was the distinct odor of something burning coming from the engine compartment but no smoke. He pulled over to inspect the vehicle. He could not determine the problem and the vehicle towed to a dealer. The dealer said there was a faulty ignition coil in cylinder three. This was replaced under warranty. The same symptoms later returned at a speed of 55 MPH. There was a significant loss of power and he immediately pulled over. The vehicle was towed back to the dealership. The dealer replaced the ignition coil in cylinder one. He offered no explanation of this ongoing problem. Updated 01/19/06. *jb
Dt: the contact states while driving at 10-15 MPH the engine began to stall, followed by the check engine light. There had been no prior incidents. The vehicle would not accelerate beyond 20 MPH. There was the distinct odor of something burning coming from the engine compartment but no smoke. He pulled over to inspect the vehicle. He could not determine the problem and the vehicle towed to a dealer. The dealer said there was a faulty ignition coil in cylinder three. This was replaced under warranty. The same symptoms later returned at a speed of 55 MPH. There was a significant loss of power and he immediately pulled over. The vehicle was towed back to the dealership. The dealer replaced the ignition coil in cylinder one. He offered no explanation of this ongoing problem. Updated 01/19/06. *jb
Also reported on the 2003 Audi A4
Fuel pump failure
Other body or interior problem
Other powertrain problem
Other speed control problem
Headlight failure or clouding
CVT failure
How far this goes
Complaints are voluntary, so 17 is a floor and not a count of affected cars. Mileages are typed in by owners and cluster on round numbers. And the mode itself is assigned by software reading the complaint text, which is reliable in bulk and fallible one report at a time.
Questions this page answers
At what mileage does misfire or rough idle happen on the 2003 Audi A4?
Across 17 owner reports that included an odometer reading, half were filed by 75,000 miles. A quarter were filed before 30,000 miles and a quarter after 90,000 miles. These are the mileages owners reported when they complained, not a prediction for any individual car.
How common is misfire or rough idle on the 2003 Audi A4?
17 reports have been filed with NHTSA, about 0.9 per 1,000 vehicles. Complaints are voluntary, so this is a floor rather than a count of affected cars.
What this is and is not. These are the mileages at which owners chose to complain to a federal agency, which is not the same as the mileage at which the part fails on every car. It skews toward failures that happened outside warranty, cost real money, or frightened someone. It is still the only public dataset that carries failure mileage at all, and the shape of a few hundred readings is informative even when a single one is not. Methodology · JSON · this failure on other cars
Source Owner complaints and recall records published by the US National Highway Traffic Safety Administration, model years 1996–2027 Figures rebuilt Published by AtWhatMileage How every figure is computed