I got a check enging light on my 95 max. yesterday. The codes are 0707
and 0304. I had replaced the thermostat yesterday and fuel filter about 2 weeks ago.

 

look where it says important at the top of this forum under ecu codes you should find your answers there!

 

Diagnostic Trouble Code 0707 points to a problem with the Rear Heated Oxygen Sensor. This sensor is mounted in the exhaust stream, just downstream of the Three-Way Catalytic Converter. When the two Front Heated Oxygen Sensors are operating properly the Rear Heated Oxygen Sensor is not used for engine control operation. It is used to monitor the condition of the Catalytic Converter. If either (or both) Front Sensors fail, the Engine Control Module uses the signal from the Rear Sensor to maintain a correct fuel/air mixture.

DTC 0707 is detected when the Engine Control Module determines that the response time of the Rear Heated Oxygen Sensor is excessive. The possible causes include ...
- Harness or connectors (the sensor circuit is open or shorted.)
- Rear Heated Oxygen Sensor
- Fuel pressure
- Fuel injectors
- Intake air leaks

Please check the condition of the wiring and connector at the rear Oxygen Sensor. If they look okay, you ought to replace the sensor. If you had a problem with fuel mixture I think you would have other DTCs in addition to 0707.

Your Maxima has three Oxygen Sensors. Two are front sensors, mounted in
the Y-pipe between the exhaust manifolds and the Catalytic Converter. One
is a rear sensor, mounted in the exhaust pipe downstream of the Cat.

When both front Oxygen Sensors are operating normally the rear sensor serves only to keep tabs on the Catalytic Converter. That's the reason your engine is running well. The Engine Control Module (the computer) is not using the signal from the rear sensor to control engine management functions.

For more information about Oxygen Sensors go to
http://www.volksparts.com/o2sensors.htm

For specific information about replacing Oxygen Sensors on your Maxima see
the Chilton manual (page 4-13) or the Haynes manual (page 6-14).

 

Diagnostic Trouble Code 0304 points to a problem with the Knock Sensor. The KS is attached to the cylinder block. It senses engine knocking using a piezoelectric element. A knocking vibration from the cylinder block is senses as vibrational pressure. This pressure is converted into a voltage signal and sent to the Engine Control Module (The computer).

This malfunction is detected when an excessively high or low voltage from the KS is entered to the ECM. Possible causes include...
- the harness or connector (The KS circuit is open or shorted).
- the KS

The KS may be checked with an ohmmeter.

1) Raise the hood. View the engine from the driver's fender. Look into
the deep valley between the cylinder banks and below the intake manifold.
Identify the KS as a black item fastened to the block by a single vertical
bolt. A wire harness wrapped in black leads toward you, out of the valley.
That is the KS sub-harness.

2) Follow the KS sub-harness to it's nearest connector. This is connector F121.
It is located near the upper right-hand corner of the valve cover of the forward cylinder bank, as viewed from the front of the car.

3) Disconnect F121. You have to do a "press the latch and wiggle and
pull" to disconnect it. F121 has only two pins; if you see more than two
pins, you have the wrong connector. Use a digital ohmmeter capable of
measuring more than 10 Megohms. You want to measure the pins of F121, not
the sockets of the matching connector. Measure the resistance between a
good ground (such as the battery negative terminal) and pin #2 of connector
F121. On my car this is the highest of the two pins, the one closest to
the front of the car. The factory spec is 500 - 620 Kohms.

The manual says you have to remove the intake manifold to replace the KS. However, I think that a person with good dexterity and a 10mm ratcheting box wrench could replace the KS without disturbing the manifold.

 

I've had the check engine light come on a few times since I got my 96 SE over the summer...
The first time, it was under the warrenty from where I bought it, so after checking the codes myself (front heated O2 sensor and Knock sensor), I brought it back and they replaced the O2 sensor without giving me any trouble.

A month or so later the light came back on, with the same codes. I reset the light, and it stayed off. It's come on a few more times, and I've reset the light then and it hasn't come back on (well, doesn't come back on for at least a month).
Anyway, I think I've linked the light coming on to the car not liking the gas I put in. I usually use 93 (not many 91 pumps around) or alternate between 93 and 89. But sometimes if I use a brand I wouldn't normally use, the check engine light comes on. Always with the front heated O2 sensor and Knock sensor, and it never gives me any trouble if I just reset it.

 

Thanks, I will tey diffenent gas statation and see if it help

 

I just had that happen to me. I usually go to a gas station near my house to get gas. One night I had to get gas at a real cheap looking gas station.

Check engine light on for about three weeks. I reset it once and it came back. I kept putting it off and after two more refills at my local gas station the CE light went away by itself just this past Wednesday.

And it was my coolant temp and knock sensors.