2004 Audi A3 2.0 TDI - when warm and allowed to idle below 1000 RPM goes into limp idle mode.(ie no response to accel pedal) Removing air mass sensor or intake air sensor/boost sensor plug allows acc pedal response and drive at reduced power. (Both of these sensors are new!) All vacuum pipes are connected to correct places and not blocked - turbo works well. Hall sender at camshaft is secure and in correct position. EGR valve has been cleaned. Injection plungers have been set and computor confirms setting as "spot on". Brake light switch has been renewed. When cold the vehicle goes like the proverbial bat! No stored errors when problem occurs! Dan Varoy

What do you mean limp mode ? This only happens with automatic transmission's . Step on gas an won't go , bog's down ????? Loses power ?????

change the MAF mass air flow sensor GBP30 on ebay

HI, your car is most likely going into limp mode. The number one cause of this computer shut down restriction- is a Mass-Air Flow sensor malfunction. Fuel trims become erratic and the engine computer puts a order in to limit performance until the original problem is resolved. The fact that you can get performance back after shutting down car and restarting is that the computer is rebooting and most likely the sensor is now functioning properly and or has not set the number of faults required for limp mode. What I would do is have someone with a scanner look for DTC's or engine problem codes, and remember the following: Lean or Rich fuel trims detected bank 1 bank 2 (is a Mass Air flow problem)Replace Mass Air flow sensor assembly. Accelerator position high or low and or erratic is most likely (Pedal sensor) Replace Pedal assembly. Good Luck.

Water Thermometer by cooling system is called Engine Coolant Temperature (ECT) sensor, and is placed in the right back side of the cylinder head on 2004 Audi A4 1.9 TDI. See picture below:




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The most likely cause is a failed mass air flow sensor and yes there is no code but if you look at the live data it will be obvious.

My 99 Audi A4 2.8 Quattro was havinga problem starting at times. It would idle poor upon start and then it would come up in rpm where it should be. I had hesitation from a start and after coasting for more than 5-8 seconds, the car would shake violently upon acceleration at about 1/3 throttle. I cleaned the Mass Air Flow Sensor. This helped but did not solve all my problems. I then replaced the Mass Air Flor Sensor. Little to no change there ($108.00). Lastly, I replaced the spark plugs. I bought Bosch plugs ($4.82 ea.). This got rid of all the symptoms. I had bad lugs and possibily a dirty MAF!

easy soloution ...disconnect the vacumn pipe going to the valve which sits on the inlet manifold and underneath it is a pipe which runs into the exhaust manifold.dont spray the water one as if you put too much water in you could hydraulic a piston and bend a con rod.either try removing the vac pipe if that doesnt work then remove the valve and block off the connection by making a gasket from a coke can but without the hole in the middle or fill the pipe up with an exhaust putty (gun gum) with a bit of tin foil on the exhaust side .promise you this will cure your problem cheaply .old vehicles never had none of this antipolution stuff on them and they ran ok.also you will still pass the emissions test for the anual inspection

check the mass airflow sensor. When bad, there is reduced power and the computer uses a default setting

you have to change the solenoid control if your car is 3.5 engine the solenoid control located at inside the transmission..