1997 Hyundai Elantra has excessive consumption of gasoline, every time the tank is almost full the check engine light turn on. Also the air bag lights is on.

check fuses and relays their are different locations for air bag sensors and their is also seat belt sensors and seat switches [check the connections under the seat ]---their are sensors under the front bumper behind the valance by the radiator support also if air bag curtains passenger side between inner fender, door and door pillar the following links have information or what to look for and assist in solving your problem the recall doesn't cover your vehicle but it pertained to the passenger air bag problem as well as the 05 posting
Why is my airbag light on 2005 Hyundai Elantra Air Bags Frontal Sensor Control Module Problems More than 280 000 Hyundai Elantras Recalled Over Air Bag Problems

Buy a new tank cap. Fill ur tank slower. Inspect the fill hose for akink or damage. And looknst the overflow vent line. Fuel caps keep air out they do need replacing once and a while. Ur take vents at the cap sounds like ur cap is not venting or ur return over flow line has issues try a new cap first. Then go deeper if issue still there chk the top of the tank where the gauge sending unit is. Etc etc.

P0563 is voltage too high possibly an alternator problem this may effect the air bag too you need to get the voltage checked

Even tho they are a certified garage they may have the cam timing off one or two teeth. I assume the check engine light is not on.
I also assume the belt did not break before you had it replaced.
I would take it back to the shop and tell them to check the cam timing.

P1401 - DMTL Malfunction
The diagnosis module comprises an electromechanically driven pump together with a change-over valve and heater. The engine management system measures the pump's electrical current consumption while pumping air into the canister and fuel tank to check the system's leakage.
If the electrical current consumption is over the threshold value specified before in the memory, this means that there is a tank-system leak.

2. DM-TL operating conditions.
(1) DM-TL monitoring operation starts only after all the conditions below are met.
A. Vehicle soaking over 4 hours and 30 minutes.
B. Engine coolant temperature over 2.3°C (36.14°F) when starting.
C. Ambient temperature between 1.5°C (34.7°F) and 40.5°C (104.9°F).
D. 6.4l or more gasoline in the fuel tank.
E. Over 20 minutes driving after starting.
F. During Air Bag is not working.

(2) And also you can check the DM-TL operation with simulation mode of HI-SCAN.

A FEW THINGS TO CHECK: OXYGEN SENSOR (DEFECT)// PCV CLOGGED// AIR FILTER CLOGGED// EMISSION SYSTEM NOT WORKING PROPERLY//

Hi,


The check engine light comes on mostly when you have bad gas tank cup,or you don't tight enough the gasoline.Go to any auto-zone and request the obd scanner,at no charge just leave your driver license or credit card,connect the scanner follow the instructions.They will check up and the check engine light will come off in the next 3 to 5 days.


Thank you !!

your problem is very easy , just go to nearest workshop , and let him delete the fault code for the air bag by the scan tool
and thats all .

Supplemental Restraint Systems (SRS) are propietary systems (meaning you can only get them fixed by the dealership (Hyundai).... SORRY!

One problem at a time. Whenever the "Check Engine" light comes on, there is always a DTC (Diagnostic Trouble Code) stored in the ECM (Engine Control Module). You'll need an OBDII (On-Board-Diagnostics) scanner to retrieve any codes recorded/set in ECM. Once you do this and let us know what, if any codes are set, then we can go from there. The AirBag light's a different story - Take the vehicle into a Hyundai Service Center (dealership), pay the diagnostic fee. They will tell you EXACTLY what the problem is and what's needed to fix it (parts, labor, tax, time-frame, etc.). Once you find out what the problem is, them maybe you can repair it yourself.