Can a rear end collision cause a problem with a front O2 sensor?

What is your question?

My car and I were recently rear ended by a careless driver who didn't notice my turn signal or break lights and accelerated into my car. He was up to approximately 35-40 mph (it's a 30 mph residential street that everyone goes 40 average on) when my decelerating (approximately 20-25 mph at time of impact) Accord stopped his Saturn Vue. He hit hard enough to crack his radiator and start leaking motor oil. My Accord took it pretty well, the body damage was confined to the rear bumper and trunk lid, however his Vue went UNDER my Accord - we found his front tag hooked to my tow hook. We did the typical pull over, turn the cars off (his permanently), call the cops, and exchange insurance. When I restarted my car, which had previously had no console lights on whatsoever and had a full tune-up in the end of January, my check engine and srs lights were on. The air bags did not deploy, but at the time I figured perhaps the force of the impact had shook something lose or just triggered a code. I figured that clearly since I was not at fault, as it was a straight-on rear-ended, my car would be taken care of and be restored to the pre-accident condition, as he has good insurance. His insurance called me the next day saying that they accepted full liability and that I should take my car to their body shop. I took the car over, had the estimate written, and made sure that I told them about the lights. The intake specialist told me that he had a slightly older Accord that was involved in a rear ender and also had those lights come on and that it was likely just error codes. Yesterday, when the shop called me to tell me that my car would likely be ready today (it was "ready") they explained to me that while the insurance company determined that the srs light came on because of the impact, the check engine light was due to a front O2 sensor failure, and since I was hit in the rear, the O2 sensor failure was unrelated to the accident. The tech then told me that they were going to try to clear the code and see what happened. I know enough about physics and cars to determine that while they could try the whole, "clear the error code" thing, I would be taking my car to my mechanic regardless of light status for a re-check. I picked up the car today and the check engine light was on. I asked the tech what the deal was with that and he told me that the O2 sensor must have been going up and that the error code occurring only and immediately after the accident was unrelated to the accident and therefore the guy's insurance wouldn't cover it. I'm taking my car to my mechanic tomorrow am, after not really driving it beyond home tonight, and plan to call an attorney for the case tomorrow as well, but my question is, can the force from a 35-40 mph rear ender (net force of approximately 20 mph) damage the heater or O2 sensor itself? I feel like this is probable, because my shoulder and neck are still stiff from the force of the impact, so my body was shaken pretty aggressively while sitting in the front seat, but I'm not a mechanic and I was hoping someone who was could share some information with me regarding the probability of this. I'm concerned that since I am not currently on PT (my doctor wants me to give my shoulder and neck two weeks to recover because of my age and general good health) no attorney will want to take the case, since the ultimate payout to the attorney would likely only be $1,500-2,500 for the case on a standard 1/3 retainer agreement. I work full-time and don't have a law degree, so I'd rather not have to do the case myself, but I am concerned that is what this will come to. Does anyone know of this problem, specifically an O2 sensor "going up" concurrently with an accident and the error code not being sent to the on-board computer until and immediately after the read ender occurred?