Mystery Oxygen Sensor

[vovo98]

Hello. Great Site!
I have a 1998 V70 non-turbo.
Check engine light came on shortly after having my small shop mechanic replace the engine with one that was 130k miles. (I blew the other one). Runs good again. Check engine light pops on. Codes are Oxygen sesor P132 and P135. Basically not working. I looked for it myself and noticed the 4 wires leading to the plug from the car had been pulled from the connector which plugged into the opposing connector going to oxygen sensor 1. Upstream. He said I needed a new sensor. I let him do it even though I also explained the wires were "out". I assumed they got pulled when they replaced the engine. New sensor and check engine is back on. Same codes. I asked about the wire leads and he assured me they were put back correct. But he could not solve the riddle. He took it to Volvo dealer and they fiddled with the plug, charged $100 and 2 minutes later the check engine was back on with same codes. They want several hundred now to figure it out. I have been looking for some wire diagram to show me which color wires hooks up to the plug in correct sequence so I can try for my self. Any ideas where I can find these colors? Thanks.