What does code P0302 and P0502 means on emission test

These codes cover 3 different areas. Misfires, cam sensors and transmission issues. I would suggest taking the vehicle to a good mechanic so they can look at it in more detail.
The Codes mean...
P0300 = Random/multiple misfires detected.
P0302 = Cylinder 2 Misfire detected.
P0344 = Camshaft Position sensor Circuit intermittent.
P0700 = Transmission control system malfunction.

I means that the vehicle failed it's emissions test as it failed the digital trouble code reading test 3
the testing station tests the exhaust emissions and the onboard computer
Your computer failed the test

Vehicle Speed Sensor (VSS) circuit low input.

Check out this link
P0502 Saturn Vehicle Speed Sensor Circuit Low Input

does code p0502 mean my transmission is bad on a 1997 cadillac deville

That is a speed sensor "a" low input code. Sometimes the sensors are external and sometimes they are internal. I don't remember specifically for your vehicle.

I would suggest monitoring the sensor with a higher end scan tool capable of reading transmission data.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Cylinder 2 Misfire Detected po302 . Evaporative Emission Control System po440 The last digit on a misfire code indicates the cylinder number. A code P0302, for example, would tell you cylinder #2 is misfiring. Chances are the misfire is due to a weak ignition coil. Did you change the pcv valve? Remember to put the o-ring on the new one or this problem will happen.

P0502 Vehicle Speed Sensor "A" Circuit Low Input

Change the speed sensor or check the wiring to it.

P0404 Exhaust Gas Recirculation Circuit Range/Performance
P0502 Vehicle Speed Sensor Low Input
P0440 Evaporative Emission Control System Malfunction
hope that helps /a little beyond my expertise but theres your codes your looking for ;)

P0440- EVAP Emission Control Sys Malfunction

Something unspecified is wrong with the evaporative emission system. Check vac lines. Could be a loose electrical connection. This code has a very vague description.


P0302- Cyl 2 misfire

Has the car had a tune up in the past few years? Check plugs and wires, test for spark. Maybe a compression test. This issue may cause the next code.


P0172- Fuel trim Bank 1 , too rich

I would clear up the misfire first, then this code might go away.


P1613- MIL Call-up circuit open/Short to B+

Check the wiring under & behind the dash and instrument cluster. There apparently is a wiring issue, or the dash itself is shorted

17704/P1296/004758
if (window.showTocToggle) { var tocShowText = "show"; var tocHideText = "hide"; showTocToggle(); } 17704/P1296/004758 - Error in Mapped Cooling System Possible Symptoms

• Cold start issues

Possible Causes

• Coolant Temperature Sensor (G62) faulty
• Coolant Thermostat faulty

Possible Solutions

• Check Coolant Temperature Sensor (G62)
• Check Coolant Thermostat

16686/P0302/000770 Contents if (window.showTocToggle) { var tocShowText = "show"; var tocHideText = "hide"; showTocToggle(); } 16686/P0302/000770 - Cylinder 2 Misfire Detected Possible Causes

• Ignition system
• Fuel injectors
• Fuel pressure
• Running out of fuel
• EVAP canister purge valve
• Evaporative emission system
• Low compression
• Base engine problems
• Controle Module damaged

Special Notes

• This feature search for engine misfire in a specific cylinder. Most of the time the cause for a misfire is a lack of combustion in a cylinder due to absence of spark, poor fuel metering, or poor compression.