t65k3

iTrader: (3)

I know it sounds stupid.... Long story short, a summary of another thread I started...... (B2=Bank2=Left Bank)

Got P0154 (ECM0509), replaced B2 front heated O2 sensor, then both P0154 and P0171(ECM0115) showed up within 30min
Replaced the Sensor corresponding to P0171 (fuel O2 sensor Bank 1)
Took off fuel O2 sensor and put the old one in (trying to see if the old one did work)
No code for a week then again, got P0154.

--I cleared the code every time i replaced a sensor.--
--I cleaned the valves that were mentioned by other members, did not see any leak.

Today, I followed the instructions in FSM and tested the sensors.
The result is kind of interesting:

When Idle.....................................When 2000RPM
B1S1 0-70mV (Mostly 70mV)...........2550mV (not changing)..............RCH
B1S2 0-750mV (Mostly 750mV)........50mV-750mV (barely changing)....RCH
B2S1 0-1000mV (periodically changing)...0-1000mV..................LEAN/RCH
MAF = 1.4V
INJ B1 (ms) = 2.14
INJ B2 (ms) = 2.40

Looks like B2S1 is working fine. 0-0.3V <--> 0.6-1.0V
While P0154 showing up the whole time.

B1S1 has a higher voltage than it should have. Why is P0134 not showing?

I assume mulfunction of B1S1 or B2S1 could mess up readings of B1S2???

Another question: where can I find this ECM terminal for me to test whether there's a short/open circuit between the sensnor harness to the ECM? Do I have to take the ECU out and find it back in there?

Apoligize for the annoying and long story, I appreciate any inputs. Thanks.

pmohr

iTrader: (26)

Where did the downstream sensor come into play? If the upstream sensors aren't reading correctly, the ECU will alter the AFR, which could change the readings the downstream sensor sees (not very much if you have a converter, possibly by a fair amount if you've got a test pipe).

You can get to the ECU harness without taking off anything more than the passenger side cover around the center console.

t65k3

iTrader: (3)

pmohr, thanks for the reply.

I will test connections during the weekend.... If they are all good, I will order one O2 sensor for B1S1, and see what happens. Hope it will fix it.

t65k3

iTrader: (3)

Checked the continuity today between pin50/pin51 and the middle pins of both sensor harnesses. It was good and no short circuit to the ground. (Man, the diagram in the FSM is kind of confusing) So… I guess the cables are ok….

Next, ordering the sensors……
http://www.oxygensensors.com/catalog...tion=To+6%2F98
I think 250-23104 is for B1S1?
I assume since it’s called sensor 1, it should be pre-cat. And bank 1 should be rear as right bank, although the part numbers are the same for front and rear.

Thanks for the help…..

BTW, just out of curiousity,
At first, the car would not start when I finished testing all the wires and put the ECM harness back to ECU. The SES light would not even be lit up when turning the keys.
After a few tries and recheck fuses, SES would lit up when I turned the key and it started fine. Why is that?

ptatohed

iTrader: (12)

Perhaps you could define P0154, P0171 and P0134 so we don't have to pull out our FSMs to follow your thread.

t65k3

iTrader: (3)

Sure,

P0154
Diagnostic Trouble Code 0509 points to a problem with the Front Heated Oxygen Sensor, Left Bank. The left cylinder bank is also called the front bank. It is cylinders 2,4,6.

The Front Heated Oxygen Sensors are installed in the Y-pipe, the part of the exhaust system which conveys exhaust gases from the exhaust manifolds to the Catalytic Converter. There is one sensor in each branch of the Y-pipe. These sensors produce a signal which varies with the amount of oxygen in the exhaust gas, as compared to the outside air. This signal is sent to the Engine Control Module which uses it to control the fuel injection system.

DTC 0509 is detected when an excessively high voltage from the sensor is sent to the ECM. Possible causes include ...
- Harness or connectors (The sensor circuit is open or shorted.)
- a defective Front Heated Oxygen Sensor.
************************************************** *******

P0171
Diagnostic Trouble Code 0115 indicates a problem with the fuel management system on the right cylinder bank. The right bank is also called the rear bank. It is cylinders 1,3,5.

The Front Heated Oxygen Sensor for the right bank sent signals to the Engine Control Module indicating an excessively lean fuel mixture. The ECM attempted to correct this problem by directing the fuel injectors to supply more gasoline. Further signals from the Oxygen Sensor indicate that the attempt to correct the lean mixture condition was unsuccessful, and the fuel mixture continues to be too lean.

Possible causes include ...
- Intake air leaks
- Defective Front Heated Oxygen Sensor
- Fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow Sensor
************************************************** ********

P0134
Diagnostic Trouble Code 0412 points to a problem with the Front Heated Oxygen Sensor, Right Bank. The right cylinder bank is also called the rear bank. It is cylinders 1,3,5.

************************************************** ********

Ref.:
1. http://forums.maxima.org/4th-generat...ease-help.html
2. ESM

t65k3

iTrader: (3)

After I reset the ECU and checked the connections, the SES has not come on for 3 days. Even there's no code, I still scanned the readings.

B1S2 stays at lean, <150mV, at all times.
B1S1 and B2S1 both are working fine, jumping between 0-0.3 and 0.6-1.0, without my replacing B1S1 sensor. Weird......

nekromansur

I hate reviving ridiculously old threads, but being a newbie I cant do jack but reply. I recently took my maxima out of storage, and even though it had slight problems in the past, I never had to take it to inspections/emissions test since I hadnt owned it for that long. Now that time came, and since the battery was dead I was rejected a handful of times, but eventually was able to squeeze by with a fail. I say squeeze by because by failing or passing I am able to insure my car to some degree, by being rejected Im absolutely screwed. The problem is that the CEL shows up with the above mentioned problem.

I ended up getting my test done today, but earlier in the morning I went to look at the CEL and check the codes. The only two that showed up were 0115 and 0509, both of those mentioned above. The car had sat for much longer than it should have and the small amount of fuel was left in there, thought maybe 0115 could be that, filled it up after resetting, went to get tested.

Upon testing, they told me that the problem code that showed up was only P0134, not P0154 or P0171. I havent checked the current codes yet, cause there were 3 systems that did not show up. Those were teh catalyst, evap and egr. In the past I had codes showing up for both the evap and the egr, so Im actually expecting as I drive this more for more codes to show up and for me to be in much deeper problems. But one at a time.

Im mechanically illiterate so Im not quite sure what all the above info means, but from what I gather, Im supposed to be replacing two O2 sensors, correct? Which ones would I be replacing, and how do I get to them? Why did the P0134 code show up, but not the P0154, or viceversa. From what Ive seen, those are two different codes for two different sensors right?

Code: P0154 | Description: O2 sensor fault