So I changed the oil and installed a oil temp gauge yesterday. That's all! (also put in new rear speakers) after I was done and was giving it a test drive - the check engine light came on. I checked the codes and was getting two codes with the plug in socket 2 - 113 and 232. According to Bently's that means a fault with the fuel injectors and compensation for rich or lean condition at idle. First of all - is that correct? It is a 1990 244DL with AW70. What could be causing this? I unhooked the battery - the light went away, but after about twenty minutes of driving the light came back on again. The car seems to be running fine, exactly like it was before the light was coming on. So, could the system really be detecting a trouble with one of the fuel injectors? How can I test to see if one of them is defective? What exactly is the code telling me? Is the system simply detecting a trouble with the wiring or something more? Thanks in advance. So far the car has treated me very well. I've kept up with all the maintenance like cap, rotor, plugs etc. They are all being changed at the recommended intervals.