Q: Flashing CEL

asked by on November 06, 2016

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.

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?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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

Leaking coolant, dripping off engine block near oil filter. 2006 Dodge Ram 1500

Hi - yes, almost certainly this is the water pump bearing seal leaking. I would replace the water pump immediately. Modern water pumps have a remarkable ability to hold water right up to the instant they fail completely - resulting...

Driver door won't unlock or lock from the inside and out. We are currently on the outside locked out

The problem sounds like the door latch or door lock is seized and will not let you open the door. You will need to get in through the passenger door and the inside door panel will need to be removed...

My car is very loud, what could it be

The presence of relatively loud noise, as well as vibration, could mean you have multiple issues. Typically, very loud operation is due to exhaust system faults but exhaust system faults will not generally cause vibration in the vehicle. To investigate...

Related articles

P0515 OBD-II Trouble Code: Battery Temperature Sensor Circuit
P0515 trouble code means there is an issue with the battery temperature sensor circuit often caused by battery corrosion or engine overheating.
P2231 OBD-II Trouble Code: O2 Sensor Signal Circuit Shorted to Heater Circuit Bank 1 Sensor 1
P2231 P2231 code definition O2 Sensor Signal Circuit Shorted to Heater Circuit Bank 1 Sensor 1 What the P2231 code means P2231 is an OBD-II generic code for the engine control module (ECM) detecting the O2 sensor signal is shorted...
P0040 OBD-II Trouble Code: O2 Sensor Signals Swapped Sensor 1
P0040 P0040 code definition P0040 indicates that there is an issue with the oxygen sensor sensor 1 circuit. This code can be in conjunction with P0041 What the P0040 code means P0040 is a specific code indicating a problem with...