Nissan Repair Questions? Ask a Mechanic for Answers ASAP
Unfortunately, the P0455 is a very "general" code that is simply stating there is a Large Leak somewhere in the EVAP (emissions control/recovery) System. So, there really is no 1-answer, "it's this..." type of answer here. I can tell you, that many times this code is set due to a loose, missing or faulty Fuel Cap (even putting fuel into the vehicle while it is running can set this code). SO first thing to do is to check the fuel cap. Check the underside of the fuel cap for any cracks or signs of defects that may keep the cap from sealing correctly. If there are any doubts about the inspection of the cap, replace it. Keep in mind, you will need a cap that meets OE Specs. Those "universal" or "locking" fuel caps sold at after market parts stores do not meet OE specs, and will not seal the system correctly. If the cap is good, then the next best course of action is to have the EVAP System "smoked". This is where a machine forces smoke through the system and the leak will reveal itself. The cost of this service varies from shop to shop with the average around $125 or so. If the smoke test proves no leaks, then there are items that will need to be tested and inspected and this will take time. So the major part of the solution here, if not a fuel cap or leak problem, will be Labor in finding the source of the problem. Labor rates vary from shop to shop, but a "fair" labor rate can by anywhere from $85-$125 per hour.