This is my first post after reading numerous posts on this site. Thanks in advance for any help.
I am the original owner of a 2002 Nissan Maxima SE with about 85,000 miles on it. About a month or so ago, it began stalling intermittently. It would stall at red lights, when coming to a stop, and at low speeds. The check engine light came on and was showing codes of P1800, vias selenoid, and P0340, the bank one camshaft sensor.
I brought it to a mechanic who replaced both camshaft sensors (bank one and two) but not the vias selenoid (he said that the vias selenoid was unrelated to the stalling). The problem was not fixed and the light came back on. I then brought it to the Nissan dealer, who replaced the vias selenoid and also replaced the camshaft sensors (which were only a week old at this point).
Shortly after leaving the dealership the check engine light came back on. The car was still throwing the P0340 code (but not the P1800 code) and continued to stall at lights, stops and low speeds. Also, although the car would run fine for stretches it would almost always stall first thing in the morning or after being left inactive for a period of hours.
I brought it to a local mechanic who cleaned the throttle body and the MAF and turned the light off (he didn't charge me for this). The mechanic said he didn't know what the problem was but that he had monitored the MAF during instances of the car stalling and was 100% sure it wasn't the MAF.
The problem came back. I brought it to another mechanic who confirmed that the throttle body was as clean as "when it came off the assembly" and looked at other possible causes but was unable to fix it (again he didn't charge me).
After discovering that there had been a recall related to this exact issue years back, I brought it back to Nissan. My car had had the recall fix performed. I hadn't remembered this but had the paperwork.
I asked Nissan to replace the camshaft sensors and crank position sensor again since they had charged me $600 and hadn't fixed the problem. They put up a fight but finally agreed to do so. They wanted to charge me $3200 plus to replace the ecu and the wiring harness (They told me they didn't know if this would fix the problem or not but that they would warranty the ecu for a year. I can't imaging putting $3200 plus into an 8 year old car and crossing my fingers that it fixes the problem).
After Nissan replaced the camshaft sensors and the crank position sensors for the third time, the car ran beautifully for one day (I left one instance out for sake of brevity
All during these issues, I noticed that my mpg was plummeting. It had never been good. It was usually around 16.9 mpg city prior to this issue but at the height of this issue was reading 14.0 mpg and even dipped briefly into the high 13s.
After Nissan did its latest replacement of sensors, the car ran great for a day. The mpg went all the way up to 18 mpg! I watched the mpg go up as I drove the car and was hopeful that the problem was finally solved, but no such luck. The next morning it began stalling again.
I brought it to one last mechanic. A state certified expert in emissions and he tested it. He said the camshaft sensor is getting the proper voltage and that the ground and other connections are good. He finally gave up and said it could be the computer or a part of the wiring harness but that he didn't know what the problem was. The engine is still throwing the P0340 code.
Sorry for the long post. Any thoughts or ideas? Before this I loved this car and hate to give it up. I am also unemployed at the moment so I can't afford another car. Thank you.