Flashing check engine light on 2003 audi A4

possible bad thermostat

The switch for reversing light is placed on the right side of the gearbox for Audi 1.9 TDI 2003 model 6 speed.
Switch: M14 x 1,5 & Part number: 01E941521A.
See picture below:


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Sounds to me like the starter is bad, if the battery is good and the connections are good and you use a starting aid and it still doesn't start.

it depends if you are driving in a hot or cold country
and check the owner manual you will get the answer

HI there,

I had the same problem with mine. Managed to determine that it was the rear brake light switch that caused a short. This meant that once the car was turned off power was being drained. We thought it might be the computer module shutting down which can take up to 10/30 minutes. But No. Replaced with a new Brake Light Switch, Problem Solved

Same thing happened to me, sounds like one of the four coils has gone cost about £40 to rplace and ten mins to fit, no special tools. The trick is knowing which one. Luckly I had a mate who had a PC with a engine management program on.

The CEL means there is a Diagnostic Fault Code stored in the Engine Control Unit. There are 1000's of DTC's, so you will need to have it read by a Code Reader. Auto Parts stores like Auto Zone, Pep Boys, perhaps even Advanced Auto often will read the code for you; but by law they cannot clear the codes. Many codes do not cause drivability problems, severe ones will trigger the ECU to run in a Limp Mode, which would require repair work before any trip longer than a few miles. Hope this is helpful.

you will have to have it hooked up to a computer to decode the light and find out what is going on. I would take it to a reliable mechanic

it's a coil- these are commonly going out on audi's...it happend to me. it's like you are running on 2 cylinders instead of 4- you need to get it replaced- it's about 75 bucks.

Yes this car should have a temperature sending unit that tells the fans to kick on. If it has two fans one of them is for you Air-condiontion, and it will turn on whenever the ac is being ran. One other possibility is if you bought the audi used the owner before you may have hard wired the fan to run whenever the car ignition is turned on. The only reason someone would do that is if they were to lazy to fix it properly.