I got rear ended two weeks ago. Bumper fell on the ground. I was at a stop light. The airbag DID NOT deploy. Insurance took full responsibility. Car was towed, while I was sent to the ER for the mother of all headaches and back pain. I got the car fixed a week later last Friday. I felt some small vibration almost immediately thru the steering wheel coming from the engine… Rpm was moving up and down slightly… Sunday was worse… Vibration was noticeable at idle… Monday was labor day… Stayed home. Tuesday the vibration was still there and it became noticeable even while I was driving… Idling was really bad. I called the collision center who got almost immediately defensive telling me that the insurance won’t pay for an engine problem if I get hit on the back period. Called my dealership to setup an appointment to see what the heck is happening. They scheduled it for Friday … Today , wednesday, was terrible in the morning. To a point where I started to call both the collision center and my Honda dealership to get some advice on the phone. Dealership asked me to wait until my appointment. Collision center stopped caring. Trip back home this evening was ridiculous. The car is vibrating at idle and while it is moving. The check engine light showed up on my way home. My AC stopped working it was a miserable drive home. I called the dealership who advanced my appointment to tomorrow morning at 7 am. The car went thru some accidents over the years but it was working great until I got it back. Any idea if a rear end shock can create such a havoc on my engine ?
Call the insurance company.
As Jtsanders said…
Call your insurance company. You pay for them to represent you when you have an accident. That’s their job.
Ditto to the already stated recommendations. You have a right to have the vehicle fully restored to the condition it was in prior to the accident, and you pay your insurance company to represent you in this quest.
You should know that insurance companies are used to claims amendments. Your situation is not unique.
Ditto above. To answer your question, a hard shock to the car can break the motor mounts and at this point, I would say that your car is no longer drivable and have it towed.
I agree with keith. Honda is not known for great motor mounts, so having one or more damaged in an accident wouldn’t be surprising at all. In fact, the same thing that happened to your neck happened to your motor mounts, if you want to think of it in those terms.
Agreed with the others. Call your insurance company.
And BTW, airbags should not deploy in a rear-end collision, so if you were worried about that, don’t 
Not only the mounts, but the trans could have taken quite a hit as well, thrown something outta whack in there.
Have the dealership scan the codes while it’s in there and see what the CEL was for, that’ll give you a better idea of what MIGHT be going on.
Call your insurance company. This so called " Collision center" is wrong. Your insurance company will pay for all damages that happen do to this claim.
An accident – even if from behind – can damage any number of car components, which could result in these symptoms. St least with the check engine light coming on, that should help your mechanic diagnose the problem.
One comment that might be helpful though. Remember it wasn’t the insurance company or the repair shop that caused the accident. The other driver was the cause. And there’s no way in advance for the insurance company or the repair shop to know what power train damage may have occurred. What I’m saying is: Neither the insurance company nor the shop are able to work miracles. It will take them some time – possibly weeks – to get this problem fixed and repaired.
It will serve your own interests better if you plan for this, and allow the insurance company and the repair shop time to do the repair correctly.
Step on the brakes for a minute!!! Before you condemn the shop wait to see what the problem is first.
Keep in mind no one here as seen the estimate of photos of the damaged vehicle. Seeing those would speak volumes.
The shop is correct in stating it would not be covered but thats half the story. If it can be proven that it is related they would pay. It is entirely possible that this is a case of bad timing.
Someone has mentioned motot mounts being the issue. You have an idea of the impact, was the bumper the only problem? If so do you really think the impact could have broen the mounts? I have seen rear bumpers shoved all the way up to the back seat and the ft of the car was ok and no mount problems
With all that said can you post the pre accident photos and also post what the dealership states is the issue?
My point is before the body shop and insurance company are totally thrown under the bus lets get some facts.
I don’t think anyone is throwing the insurance company or the collision center under the bus. The OP asked if a rear end collision could cause the engine problems and the short answer is yes. It could be the motor mounts, I have seen this in relatively minor collisions, but I too have seen some pretty bad collisions that did not result in this.
It could also be something as simple as a vacuum line that came off or got broken somehow. The advice to call the insurance company is good advice. I’m sure the dealer will find the problem and be able to determine if it was a result of the accident or just a coincidence.
When I had my shop it was not uncommon to see damage in the front of a car that was hit in the rear. Unibody cars can transfer energy from a hit to anywhere within the unibody. I have seen welds blown out on a rear frame rail from a front hit and the car did not look that bad. As Keith said, this could be anything from a wire not plugged back in to a coincidence. The shop should know better to tell a customer that a insurance company wont pay for a repair, till what needs to be repaired is known. I have seen them pay when they should not have and not pay when they should.
See if you can can get the car totaled given the new complaints, take the money and buy another. Interestingly enough air bags do not deploy as in my friends case for rear end collisions. He was in a parking garage, got rear ended by somebody going 30 mph or so, Bounced forward, broke the windshield with his head, hit the car in front then the airbags deployed, double whammy so to speak.
When cars are in wrecks, damage can turn up ANYWHERE, not just in the visibly damaged area… If you watch a slow-motion film of a collision, you will see a shock wave travel through the entire structure of the car…EVERYTHING deforms for a moment…Engines and transmissions can sustain surprising internal damage from rear-end impacts…Motor mounts are particularly vulnerable as is the exhaust mounting…
Sometimes the battery and computer are thrown out of wack…the computer system usually controls the idle…
You’re a little too late
OP never did reply after his initial post
And that was almost 5 years ago
You should be furnished a comparable rental car while repairs are made.
Yeah its been four years so if he’s still dinging around with it he has reason to be upset.