2001 Hyundai Sonata Exhaust Front Pipe

That sounds like normal pricing for both. Not sure that You need a flex pipe unless it is rusted out and leaking.

Here's a link that says to remove front exhaust pipe.

This sounds like the exhaust manifold header pipe, maybe the crossover pipe - connects both sides of a V engine to balance pressures.

These should be all steel pipe. Don't know what "hose" would be used for this. It's possible someone used a Flex pipe to repair. A bad idea. Ever get exhaust smell in car?

You need to go to an exhaust shop and have it looked at right away.
Go to 2 or 3 of them and see if they all say similar things, and similar costs. Know if you're being taken. Quotes are usually free.

Front Pipe REMOVAL & INSTALLATION Pipe Without Catalytic Converter

1. Before removing any component of the exhaust system, always squirt a liquid rust dissolving agent onto the fasteners for ease of removal..
2. Raise and support the front of the vehicle on jackstands.
3. Remove the exhaust pipe-to-manifold nuts.
4. Support the catalytic converter, then disconnect the pipe from the converter. Remove the pipe.
5. Remove the exhaust gaskets. To install:
   
6. Be sure to use all new gaskets when required. Assemble the system, check the clearance and tighten the bolts to about 15-30 ft. lbs. (20-41 Nm). Fig. 1: Front exhaust pipe connection common on vehicles with the catalytic converter not included
   
   
7. All clamps should be tightened to about 18-25 ft. lbs. (24-34 Nm). Do overtighten the clamps. If pipes become dented they can leak.

Pipe With Catalytic Converter

1. Before removing any component of the exhaust system, always squirt a liquid rust dissolving agent onto the fasteners for ease of removal.
2. Raise and support the vehicle.
3. On some vehicles you will need to remove the brace from the transaxle.
4. Remove the exhaust pipe nuts from the manifold.
5. Support the catalytic converter pipe bolts from the rear of the converter.
6. Lower the catalytic converter/front pipe assembly from the vehicle. To install:
   
7. Be sure to use all new gaskets when required.
8. Attach the new catalytic converter/front pipe assembly to the vehicle. Tighten the pipe to manifold nuts to 20-40 ft. lbs. (27-55 Nm).
9. Attach the bolts at the rear of the catalytic converter/front pipe. Tighten them to 30-35 ft. lbs. (41-47 Nm).
10. Connect the brace at the transaxle if removed.
11. Lower the vehicle.

there located in the exhaust system.i ve enclosed a diagram of your exhaust system to show you where there located, one is in the front and one in the rear, hope this helps,

Sounds like you have a plugged up catalytic converter. You cant clean them it will need replaced. If it is the 4cyl engine, the converter is the exhaust manifold on the front of the engine.

u reset the lite when u disconnected the battery. i would have the exhaust system checked asap!

Catalyst System Efficiency Below Threshold (Bank 1)

The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.

A code P0420 may mean that one or more of the following has happened:

* Leaded fuel was used where unleaded was called for
* An oxygen sensor is not reading (functioning) properly
* The engine coolant temperature sensor is not working properly
* Damaged or leaking exhaust manifold
/ catalytic converter / exhaust pipe
* Retarded spark timing
* The oxygen sensors in front and behind the converter are reporting too similar of readings


To Do list

* Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
* Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
* Inspect the downstream heated oxygen sensor (HO2), replace if necessary
* Replace the catalytic converter

it can leaking at a number of places
it could be the exhaust manifold itself or the flange where the manifold and exhaust pipe meet or at any of the joints on the exhaust pipes. or it could even be in the actul pipe itself. if you are on a tight budget you could go and ask a shop for an estimate on what it would cost to have the leak repaired.as many shops offer free estimates. sometimes the franchise shops will even fix it for free if it is a real quick fix. my wife had a flange put in for free at a shop because it only took the guy 10 min. to do it.

Start the car open the hood. with the hood open listen and smell for the leak. Probably the frt exhaust manifold leaking. Independent mechanic can repair just as easy. No need for dealer. If the leak is bad enough you will smell exhause leak. Look for the area with the greatest amount of noise.