View Full Version : 1.8t epc light/check engine light issues

03-23-2014, 02:19 AM
Hey everyone so I picked up a daily a4 while I build my s4 and the a4 needs some love. The check engine light was on for a rear o2 sensor code and an accelerator pedal position fault.

P1639 accelerator position signal and
P1118 oxygen sensor heating open circuit.

So after looking into it, I found the previous owner had no rear o2 installed on a stock ecu, so I installed a new rear o2 and cleared the light. The epc and check engine light came back on for pedal position again but my buddy that works at a dealer said hes never replaced a pedal or really heard of them going bad. He said he would more likely think before the kid removed the rear o2 the wires were broken and shorted out the ecu. Has anyone had a similar issue and what fixed it? Thanks

03-23-2014, 04:07 AM
Just because he's never done one doesn't mean it doesn't need one but you gotta test it and see get a schematic check power ground ignition and signal from Accelerator and if it's ok then check at ecu

03-23-2014, 07:12 AM
Well when we scanned the car with VagCom we watched pedal position and that all worked properly which also led me to believe that it was working properly. I have the pedal thats in my s4 that I can just swap over quick to see if that fixes it, or just pop the connector off and check the wires