Auto Insurance Claims: portion of claim denied, problem not related to the accident, air control valve, air assurance

Question
Hello, thanks for your help, it's great. It was a hit and run (culprit was never found) on major highway in heavy rain. I was rear-ended by a semi-tractor I suppose going a bit faster than I was, I was approx traveling at 50-55 mph, I spun several times, and ended up with the left side of the vehicle against the guardrail, and facing the wrong way on the highway, looking at oncoming traffic. I attempted to start the car, but it would not start, and now in I am in a panic. Finally after several attempts it did start but would not idle. I was able to work both the accelerator and brake together to keep it running and move it off the road. I then inspected everything I immediately noticed the SES (service engine soon) light was on, it was not before the accident.  After I discovered that the car was still some what drivable. I again used the gas/brake method to limp it home, I advised the insurance company and body shop of this service engine light and idle problem occurred during this accident when I delivered it to them.  Body shop takes it to the dealer (after body repairs were completed) and diagnostic’s find it needs an IACV-AAC (Idle air control valve air assurance control located on front of engine) replacement approx. $1000.00 plus the cost of the diagnostics. My issue is the insurance adjuster is saying this is not related to the accident, because of it’s location, and light damage on the left front fender. They are refusing to pay for the repair,  He states “I am responsible to pay, the burden of proof is now with me to prove it happened during the impact/accident”. Damage was mostly rear  and left rear fender, and scrapes from impacting and sliding down guardrail on the entire left side($6000.00). No physical damage to front-end, or to the IACV-AAC. I’ve paid my $500.00 deductible, $1200.00 for six weeks of rental cars and another $1000.00+ will put me deeper in the red. What are my rights?

Answer
Given the description of the damage, I would like make the same initial call as the adjuster.  The idle air control valve will not fail from the vehicle being struck, spinning around etc.  Under normal use, this valve is subject to excessive heat and much, much more jarring and constant vibration than it would have been subject to in this accident.  Other than a direct impact or long term failure, it's not likely to be affected in any accident.

Now, there are some other issues to consider.  First, when a car is in such an accident, there is a fuel pump cut off switch that is activated by unusual inertia.  Once activated, the fuel supply may be temporarily or permanently cut off until the system is reset.  While this is occurring, the rest of the engine management system may receive some unusual inputs which can cause poor drivability and all sorts of false codes to be stored in the system.  When a tech goes into the system later to diagnose the SES light, he is only going to get those codes which may lead to a wrong diagnosis.  Unfortunately, about 90 of techs will not go to the component for further diag.  They'll just look at the code and then write up an estimate for parts that are generally working fine.  Such laziness only results in more $$ for the shop's pocket.  

It sounds like it is time to have a different shop take a look at this issue.  The entire engine/emissions management system needs to be cleared and reset and the IAC code still pops up, then they need to manually test the part.

Good luck!