Gang, Still sorting out my CELs this weekend. Need to get my car smogged ASAP. I was getting the following codes: P1448 P1449 P0153 P1445 P1446 P1454 P0159 I disconnected the Thermocouples (temporarily) because the SDL was coming on frequently and the vehicle was going into limp mode. One time the vehicle stalled out completely. I was fortunate to coast to the shoulder. Let her cool off. And then fired her up and drove her home (slowly, naturally.) With the thermocouples disconnected, I'm now getting codes, P1448, P1449, P0153 and P1446. I've read a lot of posts about "just replace the 02 sensors" as one part of the process of elimination but according to the service records of the previous owner, the O2 sensors were replaced about 2 years and 15k miles ago. How long are O2 sensors good for? What can one check for? I am OK buying new sensors but before I drop 150 clams it would be good to actually know that they've gone bad? Also, others say my codes indicate my cats could be failing. Again, cats were already replaced about 2 years and 20k ago. Unlike O2 sensors, cats are expensive. I can't imagine they're already bad! What's a good DIY way to check if your cats are bad and need replacement. Obviously, given all the codes I'm getting this is going to be a long process of elimination. I get that, but I'm trying to avoid throwing my "Ferrari repair" money away replacing things that are still OK. Finally, on the thermocouples. Are these hard to remove? Mine seem seized into the cat body. Tried to wrench it out with a spanner but no dice. I will try some penetrating fluid, I just don't want to force anything and cause an expensive break. Thoughts? Guidance? thanks all. Looking for some good advice here. ketel
It's easy enough to test the O2 sensors. search youtube for testing o2 sensors. Pull it from the car, put it in a metal vise put a multimeter on the leads heat the o2 with a propane torch. watch the voltage. .8V and your fine. look elsewhere for the problem.
Here's a question - if you disconnect the thermocouples doesn't the code still get thrown and doesn't the car go into limp mode anyway? I am trying to understand the computer logic -- normally if temp is too high then cut off cyl bank but if no measurement do ?what?
Yes, you are correct (at least as far as I've observed). I disconnected the thermocouples. Now I have a blinking SDL all the time. The "limp" mode (and solid SDL) will still occur but I am finding it does not happen as often as when the thermocouples were connected. Again, I'm trying to figure out the logic here as well. I had a somewhat scary experience last weekend when the SDL came on solid and the vehicle went into limp mode for longer than usual. Typically, the SDL will come on solid, the vehicle will go into limp mode, and if I back off the throttle for 10-15 seconds-- i.e. stay in 6th and go around 50mph - the SDL will go away as will limp mode. Not that time. I got solid SDL and the vehicle limped for a couple minutes until all the dash lights came on and she stalled. Luckily, I was on a lazy country road and I coasted to the shoulder. Let her rest for 15 mins to cool off, then fired her up and drove her home. If it had happened while in a middle lane of a busy interstate I might not have been so lucky. Fortunately, this experience has not happened since I disconnected the thermocouples. I consider just plugging them back in, but given I haven't corrected the problem yet, I figure I will keep them out so I can at least continue on my process of elimination hunt of what the source of my CEL problems are. ketel
Just to give you a perspective on my own (similar) issues -- posted previously in various threads in the last 2 weeks. I bought a F355 Challenge which has straight exhaust and hence no thermocouples. When I looked at the car and did the PPI the Slow Down 1-4 light was solid on, 100% of the time. I assume(d) the Slow Down 5-8 would also be on but the light itself may be burned out... Since bringing her home I've been looking at ways to make that light go away; the CAT ECUs were plugged in but the thermocouple connection was not connected to anything, so I first tried to disconnect them altogether - no change. Now I'm contemplating adding a resistor to the thermocouple input or buying a cheap eBay thermocouple (since they are voltage generators rather than passive resistors) to trick the ECU and think that everything is ok. I ran the codes on the car and I get the 4121 code -- Catalyzer temp ECU. This is with the ECUs disconnected so my worry is that this computer code - and whatever generates the Slow Down light(s) - would cause the main ECU to choose to shut down a cylinder bank based on incorrect information.
