I have a 2004 HCH1 Manual transmission. Recently and abruptly experiencing horrible mileage and surging when doing anything other than idling or coasting. Getting DTC code P0134 -No activity from Bank 1, O2 Sensor 1. I'm assuming that without any O2 feedback it is running way too rich and that's causing the problems. The thing is, I have put a voltmeter on the O2 sensor connector pins with the engine running and the sensor is producing appropriate voltages. This suggests that the problem is a short or open somewhere in the wiring between the O2 sensor and the ECU or the ground, or a problem within the ECU itself. (Someone feel free to correct me if I am wrong or have missed something.)

So my next step it to look for continuity between the O2 sensor connector and the appropriate wire(s) on the ECU connector. To do that I need a diagram telling me which wire(s) on which connector to test. I have searched for over an hour without any luck. I'm hoping one of you can help.

(Full disclosure: It is also showing codes 1433, 1600, 1570 (battery issues) and 1679 RSCD - Radiator signal circuit error. The battery codes pre-existed the 0134 code and are most likely unrelated. The radiator code may or may not be related. I had to replace the radiator a couple weeks backs and that's when it showed. The O2 sensor code may have shown up at the same time but for a week or so, the car still ran fine. I'm not sure what caused the sudden change in engine behavior but it may have been the result of clearing the codes or disconnecting the battery when I was trying to chase down the RSCD code. I'm thinking it had some stored fuel trim data that was keeping it on track and then when I inadvertently erased it. everything went to hell. Just a guess.) .

Thanks in advance for any help you can offer.

 

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