Skip the auto shop - Our mechanics make house calls

Q: Flashing CEL

asked by on

When i start my Audia4 up the engine is rough and the car is shaking and the CEL flashes. I took it to auto zone and have the following codes. p0304, p0171, p0301,p0300. Ive been driving my moms car because i don't want to drive the audi and the audi is also leaking oil. Before all of this happened i took my car to the mechanic because my CEL was on and they charged me 600 for a new fuel injector. but now present today my CEL is flashing . i went to Oreillys to get new coils and i changed all 4 of them but it still flashes and the car is rough so I'm not sure what to do . i don't have much money for a mechanic or the dealership. and i can't trust anyone expect for the dealership but thats going to be really expensive.

My car has 128000 miles.
My car has an automatic transmission.

A: The codes you recorded, P0304, P0171, P0301...

The codes you recorded, P0304, P0171, P0301, P0300, all pertain to engine misfiring. The flashing of the Check Engine Light signifies that the misfiring is "active" (ongoing) and consequently you should try to get the car repaired before operating it further and possibly damage the catalytic converter.

Ignition coils have to be tested before they are condemned. If you did not test them, it may be that the old one were perfectly good. It is best not to replace any parts until you either pinpoint the exact fault or work with a professional to get that diagnosis. Lots of times, perfectly good parts are replaced, without testing the parts, and that is needless nowadays with the availability of not only detailed Factory Service Manuals but mobile certified technicians such as those dispatched by YourMechanic.

Here is a list of the possible faults that a mechanic would check with the codes that you have:

If you seek a diagnostic, the technician from YourMechanic will walk you through a sequence and following is a partial list of some of the items that are relevant to the codes you recorded. Note, again, that any part that is identified has to be SEPARATELY diagnosed. That is, it is never wise to replace a part just because it is on a list of possibilities associated with a code.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Why does my red brake light with exclamation mark show up when I start my 2004 Audi A4

Hello. This can be caused by low brake pad lining or by low brake fluid. I would usually start by checking the brake fluid level. If the fluid level is low then it will cause this light to come on....

Q: Car floods, have to pull fuel pump fuse to start

Hello. If your car is throwing over 20 codes, then I would stop driving the vehicle and have it serviced as soon as possible. That many codes at once is a potential indicator of a serious issue, even if the...

Q: Wheel bearing going bad

A wheel bearing noise can be identified by a loud growling noise which can get louder with increased speed. A failed bearing can also be identified by jacking the vehicle up and checking for play or movement in the suspected...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...