Hello, I need some advice for an issue I have been dealing with for the past year with my 2014 nissan sentra. The original problem that I had is engine stalling, hard starts and my car would randomly go into o/d while driving on the road. I got it scanned the code P0101 was retrieved. I replaced the MAF sensor with hitachi brand however the light came back on I thought maybe I purchased a faulty one so I went and got it replaced with a new hitachi MAF sensor but the light still came on after a few hours. I then replaced the hitachi MAF sensor with an orginal nissan MAF and the same problem persisted. I then took my car to the dealership where they updated my ECM, did a throttle body cleaning/ relearn and changed my spark plugs and coils. The next morning my check engine light came back on and I took it back to the dealership. The mechanic suggested that it could be the throttle body and that I would need to replace it however they were charging $800 just for the part alone and I had just paid the dealership $900 . I drove the car for a little and the same issues persisted making my car very unreliable because some days it wouldn’t start. Many times my car would stall and I would have to press the gas enable for the engine to stay on. I took my car to different mechanics and I have been led in circles. Starter was good brand and new battery so those are canceled out. One day after work, I got into my car and started my engine however the car would not move after switching the gear to drive. It just made a loud noise from the exhaust when I pressed the gas. I eventually got the car started and I went directly to a mechanic. He insisted it was the throttle body and sent me a link to purchase a original nissan throttle body part online that was cheaper. I purchased the part and he installed it and reprogramed the throttle body and cleared the codes. However, on my way home the check engine light came back on and he referred me to an electrical auto shop suggesting that it may have something to do with the wiring. After taking my car to the shop and paying for a diagnostic they suggested that there was a clog in my catalytic converter and that it would cost $950 to replace. They said there were no electrical issues or vacuum leaks in the system. I went to a muffler shop in hopes of finding a catalytic converter and they didn’t think it was the catalytic converter along with the other mechanics based on how my car was running. There was no code, no smell, and the air coming out of the exhaust wasn’t unusual. I bought a scanner to try and get the codes and do some research before spending that kind of money. The codes that were coming up on the car is P0123,P2135 (permanent),P2101(permanent), P0112,P0223, and P0101(permanent). After doing some research these codes have something to do with the Throttle Body. The TP% at idle is averaged at 2.7 and it does go up and down for a second. I dont know much about cars but hopefully this information is helpful. I am wondering if I purchased a faulty one online and I don’t think I was getting these codes originally with my old throttle body. However, the auto shop I went to after replacing my throttle body didn’t highlight the throttle body as the issue. I am not sure what to do or if anyone has any similar issues. I just don’t want to keep putting money into fixing the car and the issue is not actually being fixed. Any suggestions would be greatly appreciated.
If I follow your thread… the P0101 causes are:
- Faulty mass air flow sensor
- Intake air leaks
- Dirty mass air flow sensor
- Dirty mass air filter
- Mass air flow sensor harness is open or shorted
- Mass air flow sensor circuit poor electrical connection
Logically replacing the MAF seems like a smart thing to do although notice the 5th and 6th possible causes. That is important… wiring problems. Since you don’t know and can’t tell us the codes mechanic #2 saw that indicated the need to replace the throttle body I’d guess a P0123 and maybe the P2135 so hardware was replaced BUT damaged wiring COULD be the cause as the mechanic suspected when his part did not fix the problem.
The wiring shop suggested a clog in the cat… stupid diagnosis from a shop that should know better… A wiring fault… a short to ground especially… can occur when driving causes vibration and engine movement stressing the wiring. That means it is intermittent and hard to find. The wiring shop did not find it, doesn’t mean there isn’t a problem.
So now you bought a scan tool and are finding a ton of codes. All of those codes have wiring issues as one of their likely causes. That is a BIG hint. At least it is to me and should be to any mechanic reviewing your post and list of codes.
This is a difficult problem to find and fix so I’d suggest it is beyond your skills to do it alone. I’d look far and wide in your area for the best diagnostic shop in the area. The kind of shop that other shops refer to when they can’t fix things. Ask friends, search google, YP, even ask shops themselves. Research is your friend as is information.
Share what you’ve posted here with the best shop you can find and get their opinion. Be ready to pay for their diagnostic time; you want to KNOW what is wrong, not just throw parts at the problem. (You see how that has not worked!) Better to spend $350 on diagnostic time and get it fixed than toss another $900 worth of parts at it and still have the problem. Good Luck.
Thank you. I am currently looking for a good mechanic that specializes in electrical for a diagnostic. I definitely don’t think I would be able to diagnose this alone as you stated it’s beyond my reach I just hope I don’t get the run around with the next person.
Was this car ever in a crash or a flood?
Note cause #2 - intake air leaks. Have you gone over every vacuum hose and fitting, and checked for air leaks at all gaskets?
Not to my knowledge, I havent been in a car accident or flood and I have had the car for about 6 years now.
When I took the car to get a diagnostic, the mechanic claimed there were no electrical or vacuum leaks in the vehicle I made sure to ask them however it may be a possibility that there is still one of those issues. They just told me there was a clog in the catalytic converter however a few other people that have more knowledge about cars don’t think this is the case.
Clogged cats are usually diagnosed by the computer using the pre-cat and post cat o2 sensor signals. If that test failed you’d get a cat code P0420 I think is the common one. So I don’t think your cat has failed. If I had that problem and the vacuum system was leak free, pvc pcv system tested ok, egr tested ok (you car may not use that gadget), I’d want to get the fuel trims measured. Has that been done?
I think with this experience you probably discovered the “replace this, replace that” method doesn’t work so-well with new cars. Worked pretty good for pre-1980 cars, but with the computer controlled engines we have now, you can end up running out of money before running out of ideas what to the replace. Also the diagnostic codes shouldn’t be interpreted as a clue what parts is bad & needs to be replaced; they just provide a clue where to start the testing process is all. Suggest to next focus on a fuel trim measurement. You can post the results here and will probably get some ideas. Best of luck.
Those are throttle position sensor faults caused by a connector or wiring problem, not a vacuum leak. Replacing the throttle body should have eliminated a failing TPS from being a possibility.
That is not a current fault, a permanent fault is a fault that has been erased and has not occurred again. It will remain in the computer’s memory until confirmed that the condition that caused the fault no longer exists. This is similar to a drive cycle. Focus on the current and stored faults.
A quick check with a scan tool to verify the car’s computer is reading the correct intake air temperature and coolant temperature makes sense for this problem.