The "check engine" light on my 1999 Honda Accord EX came on 2 days back and so i went to aamco today morning and they told they found two codes

P1456
P1738

He recommended the EVAP Test, trans pressure test for 2nd clutch application, electrical or mechanical

This is what was written in the receipt he gave me.

Please suggest what i should be doing now ?
Are there any more such shops which do a free test and diagnosis and give a quote ? I wanted to have a second opinion so asking.

How serious are these problems and what cost of expense i may be looking at ?

 

First of all P1456 is a EVAP Control System Leak, most commonly it is a bad fuel cap, check it for cracks.

P1738 is second clutch if you want to test it yourself heres the procedure:

P1738 TCM 2nd Pressure Switch Circuit Malfunction - With Automatic Transmission
Possible Causes Setting Conditions

2nd pressure switch signal circuit is open
2nd pressure switch signal circuit is shorted to ground
2nd pressure switch signal circuit shorted to voltage
2nd pressure switch has failed
TCM or PCM has failed

Engine running in gear, and the PCM detected an unexpected voltage condition on the 2nd pressure switch circuit.

This code sets in 1 Trip(s).
COMPONENT MONITOR DRIVE CYCLE INSTRUCTIONS

Do not turn off the ignition switch during the test procedure.
All Onboard Diagnostic Monitors are cleared when the battery is disconnected or when the Powertrain Control Module (PCM) is cleared with the Scan Tool.
This drive cycle can be used to determine if the Readiness code for this Monitor will run and complete, and if the MIL will remain off after the vehicle is driven.
Operating Ranges: When a range of values is provided, try to operate the vehicle in the middle of the range. For example, if the vehicle speed range calls for 45-55 mph, drive the vehicle as close as possible to 50 mph. If the engine speed should be 1,000-2,000 rpm, try to operate the engine at 1,500 rpm.
Scan Tool Data: There are certain Parameter Identification (PID) values that must be within range before this Monitor will "run". It can be helpful to pull up those PID items on the Scan Tool so an assistant can view them during testing.
The Readiness code for this Monitor defaults to "continuous" or "monitoring" because this Monitor runs continuously when the engine is cranking or running.

COMPONENT MONITOR PRETEST CONDITIONS

MIL is off.
No Emission related DTC's are present.

TEST PROCEDURE

Connect the Scan Tool to the data link connector (DLC). Use the Scan Tool to clear any stored DTC's and to reset the OBD Monitors.
Start the engine and allow it to run at idle speed for 15 seconds.
Accelerate at part-throttle to 40 mph and maintain that speed for several minutes. Bring the vehicle to a stop, and then allow the engine to idle with the transmission in Drive (in Neutral for M/T) for 15 seconds.
Then accelerate at moderate throttle to 50 mph and maintain that speed for 15 seconds. Bring the vehicle to a stop, and then accelerate to 40 mph and maintain that speed for 15 seconds. Bring the vehicle to a stop and allow the engine to idle for 15 seconds. Repeat this step at least 5 times.
Check for any Pending codes in the Generic OBD II section of the Scan Tool. If no Pending codes are set, the Component Monitor test is complete. If any Pending codes are set, refer to the appropriate trouble code repair information to make the repair.

 

I am a new driver and have no much clue about all this. So i guess i will need to go a mechanic to get it sorted.

For the gas fuel cap, i checked and it was previously not tightened by me, it said i have to hear 3 clicks and that means it is fine. So now i have closed it back with 3 clicks but i see that it goes beyond that if i want it to, it is like there are more clicks i can make, sort of it keeps on revolving.
Bad gas cap ?
If yes then where do i buy a new one for cheap ?