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Re: Replaced O2 & temp sensors, error codes persist Posted by JerseySaab [Email]  (#666) [Profile/Gallery]
(more from JerseySaab) on Sat, 17 Aug 2013 20:04:03
In Reply to: Re: Replaced O2 & temp sensors, error codes persist, Simon S, Sat, 17 Aug 2013 15:05:39 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Yes, it was the temperature sensor between the intake runners. I really didn't think it was bad, but it's cheap and pretty easy to get to so I replaced it, would pretty much have to remove it for testing anyway.
Interesting idea about a possible bad ground, as neither sensor uses engine grounding. I checked the wiring diagram and it looks like one of the heater wires on each O2 sensor connects to fuse 28, which in turn is provided power by the fuel pump relay. The other heater wire connects directly to the ECU. (Pin 50 for the front sensor, pin 51 for the rear.)
The temperature sensor connects across pins 67 and 68 of the ECU. Pin 67 also connects to a number of other sensors, so that appears to be acting as signal ground.
Looking at the ground distribution part of the wiring diagram, it looks like the ECU and O2 sensor heaters share a ground point indicated to be on the left side engine bracket. That probably bears looking into, as well as checking for continuity between the front sensor heater and pin 50 of the ECU.
The P0125 code (low coolant temperature) may turn out to be the thermostat. It's hard to tell since the temperature gauge on the dash is buffered by the ECU, but I could be convinced that it is reading a little lower than before. Though before going through the trouble of replacing the thermostat again, continuity between the temperature sender and ECU should probably be checked.
Glad I remembered that wiring diagram, at least now I have something of a game plan for diagnosis. It looks like I have some circuit tracing fun ahead of me...
->Posting last edited on Sat, 17 Aug 2013 20:30:38.
, Sat, 17 Aug 2013 08:12:07, Mon, 19 Aug 2013 18:32:44, Thu, 22 Aug 2013 16:01:17
, Mon, 19 Aug 2013 13:40:44, Mon, 19 Aug 2013 14:41:54
, Mon, 19 Aug 2013 15:47:31, Sat, 17 Aug 2013 08:56:09, Sat, 17 Aug 2013 09:00:29, Sat, 17 Aug 2013 20:04:03 <-- Viewing This Message, Sun, 18 Aug 2013 12:28:54, Sun, 18 Aug 2013 15:23:18, Sun, 18 Aug 2013 17:13:41, Sun, 18 Aug 2013 18:19:04, Sun, 18 Aug 2013 19:36:05, Mon, 19 Aug 2013 04:44:42, Mon, 19 Aug 2013 04:50:31, Mon, 19 Aug 2013 06:02:42, Mon, 19 Aug 2013 06:32:28, Fri, 19 Oct 2018 15:04:12
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