can getting rear-ended damage transmission

Is it possible that getting rear-ended can damage the transmission?
94 Mercury Sable, wagon.
The car got rear-ended at a stop sign, enough to bend the bumper. About
a week or two later the transmission refused to shift above 2nd gear. Added transmission fluid - too much as it turned out, and it poured out for a while making clouds of black smoke. Drove OK after that (about 100 miles - had to get home). Would not go above 2nd, but drove fine.
Now the transmission started slipping, and the car is not drivable. It seems to be stuck in 2nd, but I'm not sure.
Took it to a transmission place and the mechanic said something about the hydraulics, and need a new transmission.
Also, the service engine soon light went on when it first happened, but not after, but the only codes that were read were 172 and 176, the mechanic didn't know what they are.
I looked them up and they seem to be about the oxygen sensors, which doesn't make much sense - why would the light go on, and the transmission fail at the same time, yet the code be about an oxygen sensor?
Can anyone help me either diagnose the problem, or tell me if it was caused by the accident? If it was the accident, then it should be an insurance claim, but I need to know if they are related.
    -Ariel
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sensor?
I think the transmission problems are not related to the crash. Anyway, you don't have to convince me, you have to convince the insurance adjuster. You can call the insurance adjuster and tell him that your transmission is broken as a result of the crash. Let him prove it isn't.
The problem you had the check engine light is probably just a coincidence, as well. It is not that unusual for a check engine light to go on for a few miles (or a few hundred miles) and then go out. It doesn't mean anything.
Jeff
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Snip
On rear wheel drive cars when you get rear ended the engine/transmission slams into the drive shaft. Can damage the rear axle and/or transmission.
Al
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Ariel wrote:

As the other poster noted the engine codes a likely coincidence. Take to a transmission shop you can trust and ask them if you could have a vacuum leak.
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wrote:

The engine codes are quite possibly related to the rear end collision. Check the exhaust VERY closely for kinks. I've seen more than one minor punt crimp the exhaust to the point O2 Sensor codes are thrown, and shifting goes funny (due to reduced engine vacuum, or increased back pressure (both cause a reduction in cyl filling)
I have also seen shift solenoid failures due to impact - so do NOT rule out transmission damage from a rear-ender. However, this kind of damage should not require replacement of the tranny - just the solenoids
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VERY, VERY unlikely that a minor rear end collision would damage the transmissions operation. Damage from that type of impact, if serious enough, could cause physical damage to the tranny, but more in the nature of damaged seals or cracked tailshaft housing. To damage the trans from a rear end impact, you would likely have to hit the vehicle hard enough to have demolished the entire back end of the vehicle. The transmission operation would be the least of your worries and the vehicle would not have been drivable.
However, overfilling the transmission CAN cause internal problems in the transmission and will "foam' up the fluid. Overfilling may cause the fluid to foam up and out the dipstick tube, and will also result in excessive smoke, as the engine will suck and burn the foamed transmission fluid through vacuum lines, however it should be white or whitish-blue and would go away after the excessive fluid is burned off.. (This will also cause the "check engine" light to come on)
Black smoke is indicitive of too much fuel. The burned transmission fluid flowing through the exhaust as smoke can permanently damage, or cause the Oxygen sensor to malfunction and send a "too lean" signal to the computer, causing the fuel system to respond with a richer mixture...resulting in black smoke from the exhaust. (These will cause a "check engine" light as well)
Replacing the 02 sensor may correct the black smoke condition, but the sensor should be bench-tested first as it MAY just be correctly reporting a "too rich" condition caused by another component.
Check the vacuum hose on the vacuum modulator on the side oif the transmission. If it has ANY trace of transmission fluid inside the vacuum hose, the modulator needs to be replaced. It will effect proper shifting.
Slipping, however is just a sign of old-age and regular wear and tear, or a failed internal component, not accident-related.
You always want to make sure you added the correct type of trans fluid to the vehicle as outlined in the owner's manual or the dealer recommendation, and NOT just what it says on the can.
Good Luck!

sensor?
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