t65k3

iTrader: (3)

CEL was on, ECU gave me a 0509 two days ago. Had a shop to replace the front heated O2 sensor for me today.

15min of driving, CEL was on again. Now it's 0509 and 0115.

After a bit for search, found this useful thread,
http://forums.maxima.org/4th-generat...ease-help.html

Now I am suspecting it's not just the O2 sensors. It might be one of the possible causes,
- Intake air leaks
- Defective Front Heated Oxygen Sensor
- Fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow Sensor


This all started in about 20min after I put in a new tank of gas. Would it be caused by bad gas? Any suggestion?

Does anyone happen to know the reasonable price for a heated sensor?

Thanks.

t65k3

iTrader: (3)

http://forums.maxima.org/4th-generat...ms-fix-me.html

found this one with search "P0171"

since both banks have the codes now, I guess MAF is my best bet at this moment.

t65k3

iTrader: (3)

Had almost everything I read about thie issue checked ......
Plug in new O2......
But the code is still there containing 0509 and 0115......
When scanning with OBD II, P0174.... running lean.... voltage on the right bank was not changing much, stayed at ~0 the whole time......
Though the left bank had a new O2 and the voltage was changing in response to the gas I gave, there's still 0509......

This whole problem happend 20 min after I got full tank of gas from Walmart about a week ago. It was about 2/5 of tank gone this morning, so I topped it off with good Shell gas..... Man, 12MPG, suddenly I got a V8.......

Next thing to do: check if there's smoke coming out of pipe....

I am gonna need some luck......

Carrera

could be an intake leak. have the car running and spray carb cleaner or brake clean around the intake manifold seals, upper and lower and if the idle fluctuates, then thats your problem. Worth a shot

maxima_million

Ok, this is wierd: I too pulled 0509 and replaced the front 02 sensor. About 10 days after, the 'Check Engine Light" came on and I pulled 0509 AND 0115. Today it took 3 tries before the engine turned over and I smelled raw fuel as well. I have not tried any of the suggestions mentioned on this thread but plan on doing so maybe next weekend!

Thanks in advance for those who are troubleshooting this as well!

t65k3

iTrader: (3)

at least, you enjoyed 10 days without worries.....
My second 0509 along with 0115 came up only minutes after I replaced O2 for first 0509.......
I heard hissing sound when the engine's running. I kind of noticed that before but didn't pay attention. Maybe there's some leak somewhere I overlooked......
I need to get a new MAF, because it kind of makes sense to me..... if MAF goes bad, both O2 will detect something weird......

t65k3

iTrader: (3)

Replaced both O2s.
Still got the code for some reason.
Cleared it.
No code so far. It's been almost a day.
But I can tell it's still dumping too much fuel by the smell....
And... I am almost sure the code will come back.....

The output of front O2 is not changing much.
When I hit the gas and maintained around 2000rpm. it started to work like the scanner said, "between rich and lean. 5 times/ 10second"
When rpm drops, it stopped again.
Any suggestion?

t65k3

iTrader: (3)

Weird.... CEL has not been on for four days, voltage for O2 reading was not quite right for the time that I cleared the code. I have only replaced one O2 sensor.....

t65k3

iTrader: (3)

CEL came back on after 1 week of peace...... 0509......

Check Secondary Intake valve?