We just bought this truck, it has 108,000 miles on it. It passed its inspection, but not the emissions. We have three weeks to get it to pass in VA. I am really frustrated, as I shouldn't have bought it without it passing emissions, but here we are so, oh well. My son took it to the station where he works, and he plugged in the emissions tester and the catalyst and evap sensors wont transmit. The station, told him to just drive it around till they light up and then they will pass him, but 1 1/2 tanks of gas later and this hasn't happened. So....now he has ordered all new spark plugs and egnition coils to replace the ones in the truck. He says it needed them anyway. He hasn't put these in yet as we have been hit with the blizzard and he wants to do this with his auto tech teacher. This truck has added to it a modded computer, and a snow plow control arm, and snow plow interior control joy stick and is wired for a heavy duty snow plow. There is no snow plow on the truck now. I just need it to pass emissions in the next three weeks to get it tags, any help, I would appreciate. I don't understand this, just keep driving it, advice. This is a licensed emissions tester and repair station, so I can't quite figure out why they wont say, you need to fix this and then it will pass. Thanks in advance.my son is 16 and just started auto tech classes at high school and volunteers in this shop for experience, he wants to be a preformance car mechanic some day

 

if you have O2 sensors , CATS or something else not working, you should have a code light on the dash. When plugged into a scanner, the "code" will give you a 4 digit number and that will lead you to the cause of the problem. If you have a code, the shop needs to read it and tell you what it is...... Randomly driving around does not fix anything.

 

Thank you for your reply, my son says the catalyst sensor and the e vap sensor are not coming on at all, i am not a mechanic at all, i am a veterinarian, so if this doesn't make sense, help me out with what he should be telling me, i just want this fixed, if i need to take it to a different place to get better info, that works for me

 

What a great learning experience for your son!


I think what your son (or the shop is trying to say) is NOT that the sensors are not coming on, but that the CAT Monitor and the EVAP Monitor have not run. The vehicle's computer has special programs, called Monitors, that run (or execute) under specific conditions, and verify that the various systems, such as the Catalyst System and EVAP System are correctly functioning.


For example, one of the things the EVAP Monitor verifies is that there are no leaks in the fuel system. It does this by drawing a vacuum on the fuel tank while the vehicle is running and seeing if the vacuum holds for so many seconds. In order to achieve accurate results, this monitor will not run if the ambient temperature is less than 40*F or if the fuel level in the tank is not between 1/4 and 3/4 full, as fuel slosh or cold temps will effect the vacuum level reading and throw the results off.


I don't know what the specs are for the VA inspection but some states will allow a vehicle to pass emissions if one monitor hasn't run, as here in New York State we may not get above 40*F for weeks or Months at a time.