For a while now I've been getting a 0505 code and I'm not sure why. I'll reset it and maybe 10 miles later or the next time i start my car its back again! Has anyone else had this happen to them? I just replaced my knock sensor so i know it can't be that. What else sets off the 0505 code? Its really annoying because then I don't know if there is a real code that has gone off or if its just that annoying nothing.

 

0505 = no problems detected


Is the light on or are you pulling codes with the light off?

 

Go to an OBD scanner. They might pull some ghost codes that your cel doesn't show.

 

yea 0505 means everything is good

 

I know that a 0505 means everything ok. I pulled the code again and this time I get 0901 and 0905. o2 sensor and cps(pos). I've replaced both of this and I am still getting the codes. I checked the fuse for the o2 sensor and even put a new one in just in case and still no good. And I know it can't be the harness because When I was away at school the dealer convinced my dad that it was broken and had to be replaced so he shelled out and put a new one in. Both codes never show up after I clear them right away. It's always on the 2nd start after I've cleared them that they come back, never fails. Even after driving around for a goor hour they wont light up till the second start.

Any ideas where to go from here? Its really frustrating. Has this kind of thing happeded to anyone else?

 

A weak starter can cause a CPS code... Does your car crank normally? (it could also be a weak battery I suppose).

Which o2 sensor have you been replacing?

0901
Diagnostic Trouble Code 0901 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.

The one you *should* have replaced for this code is the on in the y-pipe closest to the firewall...

 

Oh ya - which CPS did you replace... there are two (REF and POS)... one is in the tranny bell housing and one is right below the crank pulley on the passenger side of the engine.

I can't remember which is REF and which is POS, but IIRC, the one on the tranny housing is the POS.

 

The car starts strong. I had to regrease the starter last summer and my car still starts on the drop of a hat ever since I got my optima red top.

I replaced the upstream sensor closest to the firewall, not the one right by the fan. I have a Cali spec so I get the pleasure of dealing with four of the little guys. |_|__ <--- If thats the y-pipe i replaced this one, |_*__.(if that makes sense)

I also replaced the CPS POS sensor, thats the one in the tranny bell. Thats the one my haynes manual said was throwing the code, unless its different for cali specs.

 

Well it looks like you've done the right things (in terms of sensors)... The reason come codes don't get posted right away is that the ECU likes to see the failure a certain number of times (varies for each sensor), before posting the CEL code.

You need to start getting more sophisticated - i.e. start measuring voltages at the ECU from the O2 sensor and CPS - something is obviously not right.

 

I just checked my o2 sensors with my multimeter and I was getting around 4.6ohms for the front right and 5.8 for the front left. The rear senors were ok. If I were to switch the sensor in question to the rear then the code would pop up for the downstream sensor? This could also help me figure out if my wiring is bad of if the sensor is. Think it would work or do rear and front sensor sense differently? I might get under my car and check the cps later.

 

You can swap the two fronts, but the rear is different.

That's a good idea (to swap the o2 sensors) - see if you get a code again and see which sensor it points to. If the code moves with the sensor (to the new location), then you have a bad sensor, if you swap the sensor and get the same code, then you have a wiring issue.

 

So much for switching sensors. I took a look again and noticed that all four sensors are different. None of the harnesses will plug into each oter so I guess I'm out of luck with that one. I love my car but sometimes I just hate it, or rather just hate cali specs!

 

Two of the fronts should be identical... at least they are on the Fed Spec...

Are you sure? Just go to www.oxygensensors.com and see what part numbers they list for each of the 4 sensors - you will find that two of the sensors are the same part number...