P0301, p0117, p1258
03-17-2018, 05:37 PM
#1
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P0301, p0117, p1258 HELP!!! Just did new plugs and wires. Had the P0301 code before then it would intermittently come and go. Now I have these three codes P0301, P0117, P1258 and don’t know where to start. Ordered new 02 sensors and going to do a compression check next. Is there anything else I should look for? I have a ticking but not sure if exhaust leak of valvetrain noise at this point. The misfire is hardly noticeable if there even is one. Car doesn’t struggle with power or burn oil
03-19-2018, 02:52 AM
#4
DTC P0117 and P1258 are related to engine temps. If the temp sensor is reading higher than 270*, the PCM will engage the protection mode which could cause misfires. If the car is not showing signs of overheating, I would check your temp sensor for correct operation. I attached DTC troubleshooting charts that may help. You don't say what your working on. It may be possible there are two temp sensors, one for the gage, the other for the PCM.
Last edited by peterpar; 03-19-2018 at 02:57 AM.
03-19-2018, 08:44 AM
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Although possible, coolant temp sensors rarely fail. I would look for damage/connection issue with the wiring for the temp sensor. May have caused the problem when doing the plugs. If the cyl 1 misfire returned, I would swap coils with a good cylinder and see if the fault migrates.
03-19-2018, 10:11 AM
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Thanks guys! Going to replace the temp sensor that plugs into the front of the head by cylinder 1 and check the wiring as well. Is this the only sensor I should worry about? I read there’s one inside the water pump as well?
03-19-2018, 09:36 PM
#7
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Update Replaced temp gauge and all three wires leading to the sensor were exposed copper tried rewrapping them and still the same issue. With check gauges light this time. Is is a possible short or is the new 35$ sensor a POS? Just purchased a new pig tail on amazon to be sure
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03-19-2018, 10:20 PM
#8
Without knowing what year of a car and motor, it's really hard to get much more specific. Early model LS1 ECT sensors have three wires, later have two, so I'm assuming your car is maybe a 98? I've attached schematics that show the sensor connector pin locations. Check to make sure you have the connector wired right.
Last edited by wssix99; 03-25-2018 at 09:29 AM. Reason: removed copywritten attachement
03-19-2018, 10:46 PM
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So the three wires were damaged before you changed the sensor? Melted or chaffed? A picture of the damage would be great. Even if those wires short out it won’t melt, it runs off a 5v reference. There is a 5v reference from the ecu, a modified signal return, and a temp signal for the cluster gauge.
03-20-2018, 12:53 AM
#10
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The 3 wires had about an inch or two of just exposed copper right by the plug where the insulation was missing on each one. If the copper touches one another it will short right?
03-20-2018, 01:31 AM
#11
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If it were mine, I'd unwrap the entire harness back to the pcm, and replace all 3 wires from as close to the pcm as possible. You really need to dig into that harness because that short you had could have fried something else in the harness too, which could explain your misfire. Don't forget to check your grounds too and replace as necessary.
You might want to start gathering tools to do this job right. Don't forget to order some proper wire braid too. Summit sells lots of different kinds and sizes. It looks good and won't wear out and crack like the old factory stuff. Do it right. Open that harness and check for more damage.
03-20-2018, 08:00 AM
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Correct. You need to unwrap the harness back to clean wire and replace everything that is damaged. The wires touching each other are causing your coolant temp fault and your check gauges fault. I, too, recommend uninsulated butt connectors with heat shrink. I’m talking about the quality double crimp connectors not the cheap ones from the parts store. Others prefer soldering, or soldering in the cheap style butt connectors...those are both effective if you know how to solder effectively.
03-20-2018, 08:09 AM
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Not sure what caused the damage. Now I’m worried this thing caught on fire at one point haha but I bought a new temp sensor pigtail and will reconnect it back to the main loom that follows the fuel rails back. The other 2 re-wrapped wires are the water pump and upper 02 sensor. The car is my DD so going to be a PIA to do everything that’s not damaged
03-22-2018, 09:50 PM
#15
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Okay guys I replaced the coolant temp sensor and the pig tail but still getting a check gauges light and the water temp was pegged. How Can I test if the sensor is getting a good connection? Is it just a bad sensor?
03-23-2018, 12:25 AM
#17
No, the 98 has only one sensor, but it has two thermistors for separately controlling the dash gage and the PCM functions. Is the engine actually overheating or just the gage showing it hot?
03-23-2018, 09:06 AM
#18
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The gauge is just showing hot. Before the new sensor and pigtail the gauge would jump all over the place and try and stall out but now it’s constant hot. I spliced the existing wires and crimped in a new pigtail matching the colors on the wires.