OBD-1 Port not working! Please HELP!

[hammer_e30]

I have an '89 325is . Today I went in for an emissions test. It failed on the idle test only. The check engine light would come on intermittently and the code from the stomp test was 1222. I replaced the O2 sensor and cleared the code with the Peake R5 code reader. Took it out for a 20 minute drive and everything was great. I parked it and about 2 hours later, took it for a trip to Wally World. On my way there, the light came on and stayed on. When I got to Walmart, I did a stomp test and the code read 1264, which is the EGO Heater (O2 Sensor Heater). The relay is fine and the O2 sensor is brand new. I have the Miller MAF conversion done and it's been on and running ok. The check engine light would come on if I was cruising in between 1.5K and 2K RPM's sometimes, after the conversion was done. Also I have poor fuel economy on the highway. I used to average around 27 MPG on a long trip doing about 80 the whole way. Now I can only average about 20 MPG. Anyway, my R5 code reader is now not working when I plug it into the OBD port. I'm not sure if this is the chip, the conversion, wiring, or if the ECU is crapping out and causing all of this. Any help would be greatly appreciated.

[jlevie]

The first thing to try would be to replace the relay. The DME can't tell if the heater actually works, but it can tell if the current flow through the heater relay coil is not correct.

While replacement of the O2 sensor was probably warranted (the sensor has a useful life of not more than 100k), I suspect that the 1222 code was from an intake leak rather than the sensor. A smoke test of the intake is indicated.

[hammer_e30]

I did swap the heater relay with the fuel pump relay. They both seem to work fine. The 1222 code must have been an old code because I just replaced my intake manifold gaskets because of a vacuum leak. The car runs much better now. I did however check the power going to the relay and there is none. I think it was reading .60 VDC. I'm not sure if it's in the wiring harness or the the ECU, because since this code was thrown, the OBD port doesn't work now.

[DaveSmed]

Check fuse 9, powers both the diagnostic connector and the oxygen sensor heater.

[hammer_e30]

Hey thanks DaveSmed! That's all it was. Why is it that you always consider the worst case scenario before looking at the basics? Then again, Bentley doesn't really say that fuse 9 powers those things. Thanks again though!