Last post on Oct 22, 2013 at 2:53 PM
You are in the Maintenance & Repair
What is this discussion about?
Fuel System, Electrical, Engine
#1697 of 1702 what could possibly go wrong?
by MrShift@Edmunds HOST
Jul 28, 2013 (6:38 am)
...as the orchestra on the Titanic strikes up "Nearer My God To Thee".......
The author wonders if GM execs don't know or don't care and the answer is....both.
#1698 of 1702 Re: check engine light on/ codes P0420 AND P1245 [fendlay]
Aug 22, 2013 (5:41 pm)
Try changing the gas cap. sometimes older cars have a cap problem and it sets off the sensor
#1699 of 1702 Re: check engine light on/ codes P0420 AND P1245 [fendlay]
Aug 23, 2013 (4:18 am)
You can do some sleuthing as to the origin of the light or you can take it to a box store that does free code checking to see what code is showing that's turning the light on. Don't buy anything based on the code, just report it and let some folks try to help narrow it down.
The items besides the gas cap leaking that can cause codes are the purge valve and the vent valve along with some rubber tubing that carries the vacuum to the tank to do emissions checks.
The rubber parts deteriorate and crack causing a leak of the vacuum setting off certain codes. Heat above the engine aggravates the aging.
The purge valve may not be turning on to send vacuum to the charcoal cannister to let air flow through to remove gas vapors caught in it.
The vent valve may not be closing for the times when the emissions check verifies that there are no leaks in the tank, cap, tubing, etc., to allow the gas fumes to vent to atmosphere instead of being forced throught the charcoal canister where they will be caught by the carbon granules.
There also is a pressure sensor on top of the tank that measures the vacuum drawn on the tank/system by the purge valve and how quickly that vacuum deteriorates (measuring the leakage of air into the system).
Also note the relationship to the volume of fuel in the tank. The typical GM algorithm is to only run the leak tests when tank is between 15% and 80% or so in gasoline. Also the engine needs to be luke warm--not cold and not full normal temp. Try keeping your tank between 1/4 and 3/4 for a couple of weeks and lots of key starts. See if the light goes off because the system is able to correctly do several leak checks. The computer has to do a certain number of good tests before it will turn off the light.
#1702 of 1702 Re: on-off engine light [autoexpert2]
Oct 22, 2013 (2:53 pm)
thx-it turned out to be an air fuel sensor-spent close to $600 to get it replaced at a Toyota dealership.Hoping to get a few more years out of my 14 year old Sienna with 200k on the clock. Gotta admit though this car is getting expensive to keep on the road