Audi Repair Questions? Ask a Mechanic for Answers ASAP
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The EPC (Engine Power Control) light is a check warning light for the electronic throttle control. This vehicle has a "drive by wire" throttle control rather than a mechanical cable as in year past (<1999). The on board diagnostics of the Engine Control Module (ECM) must be scanned with VW/Audi capable scanner to check for stored Diagnostic Trouble Codes (DTC). Further testing and repair will be dictated by any retrieved DTCs.
One thing you could try as an owner would be to disconnect the battery cables, hold them together, then turn on the ignition key to the on position for 30 seconds or so, shut off the key, reconnect cables. You can adapt the throttle in this vehicle by turning on the ignition to the on position (do not start). You should hear the throttle (top, rear of motor) go through it's adaptations. It only takes about 10 seconds. Now start the vehicle and drive as normal. If the EPC illuminations return further repairs will be necessary.
A cleaning of the throttle body butterfly valve followed by an adaptation of the throttle with a VW/Audi capable scanner may be attempted. The advantage to using the scanner is that you see the throttle go through it's adaptations, followed by a pass, or fail. Unless the throttle was significantly contaminated, the fault returns more often than not. It has been my experience that the throttle body assembly has usually failed and is replaced as a unit. MSRP for the unit it $625 and replacement should take approximately one hour (diagnosis/confirmation not included).
If immediately following "jump starting" of a dead battery the EPC is illuminated, a failed throttle body is also the likely cause.
If the idle fluctuates or is too low, a cleaning of the throttle body could correct the situation, but usually the EPC light will NOT be illuminated in this case.
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