I diagnosing the ECU for the engine codes, it came up with 0103 (which I checked is the Engine Coolant Temp Sensor) and 0402 ( Fuel Tank Temp Sensor). BUT the thing is.. there seem nothing wrong with my car.. my temp guage is operating normal and the fuel tank guage is operating normal..

the question is: Should I still replace these parts? How easy is it to do it yourself? Or should I just bring it to the dealer and have it repaired? Or should I just order the replacement part online and attempt to do it myself? ANY comments is appreciated...

 

try resetting the ECU and see if the codes come back....

 

I did reset the ECU.. and the light came back on.. but I didnt check for the codes again.. figuring it is gonna be the same codes again..

 

Diagnostic Trouble Code 0103 indicates a bad Engine Coolant Temperature Sensor, or a defect in the connector or wiring. There are two sensors, one for the gauge and one for the Engine Control Module. It is the second of these two which is causing trouble.

Your fuel injected engine has an Engine Coolant Temperature Sensor. This
sensor sends a signal to the Engine Control Module (the computer). When
the ECTS sends a "cold engine" signal the ECM responds by instructing the
fuel injectors to deliver a rich mixture. The rich mixture helps a cold
engine to start and run smoothly during the warm-up period. This is similar
to the operation of the choke on a carbureted engine.
There are other problems which cause cold starting and driveability
problems, but the ECTS is the first thing to check. This can be done with
an ohmmeter.
On the 4th Generation Maxima engine the Engine Coolant Temperature Sensor is
located in the water outlet tube close to the engine end of the upper
radiator hose. There are two sensors in that vicinity. The one nearest the
hose is for the dashboard temperature gauge. The ECTS, the one you're
interested in, is adjacent to the the gauge sending unit. There is a good
picture of these sensors in the Haynes manual on page 3-7.
With the engine cold, disconnect the ECTS and measure its resistance.
Reconnect the ECTS, start the engine, and run it until fully warmed up. Stop
the engine, and repeat the resistance measurement. The "warm" reading should
be a much lower value than the "cold" reading. These are the specs:
Engine coolant temperature 68F, ECTS resistance 2.1 - 2.9 Kohms
Engine coolant temperature 194F, ECTS resistance 0.24 - 0.26 Kohms
(Roughly a factor of ten difference.)
The ECTS is a relatively inexpensive sensor and something the home mechanic
can replace without special tools.

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coudltn find anything helpful on the 0402 code.....also, does your car start now?

 

yes.. the car starts now.. all it needed was a jump start.. since the car was sitting there for about 2 weeks.. stupid me thinking that I f**ked things thru messing with the ECU...

I dont really have the Haynes manual.. I guess I am just gonna bring to a local mechanic and have them check for what you just told me..

Hey.. thanks for your help..

 

I just went through this myself...

Conventional wisdom on the board says that you replace the ECTS first as it's relatively inexpensive to have done, and easier to do by yourself.
Also, ECTS can cause false KS readings, so KS may go away after ECTS fix.
OTOH, you may still get KS by itself, so you'll need to go after that one later. The dealer wants "a lot" of labor $$ to do this.
There is a writeup on how to do this yourself relatively quickly at the expense of some cuts and scrapes.

The symptoms that you'll experience are lower gas mileage and loss of power, derived from the KS error. A relatively simple test might be to reset the ECU and before the codes reappear, see if mileage goes up (it will reappear before a full tank is used probably) or "feel" if power is up. IMHO, it's noticeable.