850 turbo won’t warm up after thermostat and ect sensor change
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snugani
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- Year and Model: 1996 855 turbo
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Yesterday I changed the tstat and sensor, now it won’t go above 1/4 of the way to warm. The harness side connector came apart, so I cleaned the bullet connectors and pushed them onto the new sensor connector posts, and wrapped it in electrical tape. It’s strange as it worked before I changed these two. Any ideas?
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RickHaleParker
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Copper wire corroding under the insulation. When you moved the wires you broke some strands. Check for high resistance on wires to the sensor.
Often you can tell by looking where exposed copper meets the insulation.
Often you can tell by looking where exposed copper meets the insulation.
Active
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2017 Ford PIU. 3.5l, Twin Turbo, 365 Hp.
............................
Past
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000. ( Killed by a plastic radiator. )
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion ( I moved, the project did not )
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0. ( Transmission dead after sitting for a winter )
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2017 Ford PIU. 3.5l, Twin Turbo, 365 Hp.
............................
Past
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000. ( Killed by a plastic radiator. )
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion ( I moved, the project did not )
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0. ( Transmission dead after sitting for a winter )
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RickHaleParker
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Post a picture of it, without the black tape. It does not take much to mess up an electrical connection.snugani wrote: 01 Aug 2026, 11:50 The sensor itself is new, the wiring itself on the harness side looks to be intact
Use an Ohm meter to check for high resistance.
Also take an Ohm meter and measure the resistance of both the old and new sensor.
Active
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2017 Ford PIU. 3.5l, Twin Turbo, 365 Hp.
............................
Past
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000. ( Killed by a plastic radiator. )
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion ( I moved, the project did not )
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0. ( Transmission dead after sitting for a winter )
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2017 Ford PIU. 3.5l, Twin Turbo, 365 Hp.
............................
Past
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000. ( Killed by a plastic radiator. )
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion ( I moved, the project did not )
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0. ( Transmission dead after sitting for a winter )
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erikv11
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Rick's comment is in general a good one but also, the wires in this particular ECT connector/harness are known to commonly fail due to corrosion.
What brand is the ECT sensor? Aftermarket ones of these can be especially bad. Taking the resistance measure will help on that front.
What brand is the ECT sensor? Aftermarket ones of these can be especially bad. Taking the resistance measure will help on that front.
'95 854 T-5R, Motronic 4.4, 185k
'98 V70, T5 tune-injectors-turbo, LPT engine, 304k, daily driver
'06 S60 R, 201k
'07 XC70, black, 205k
'07 XC70, willow green, 223k
gone: '96 NA 850 210k, '98 NA V70 182k, '98 S70 NA 225k, '96 855 NA 169k
'98 V70, T5 tune-injectors-turbo, LPT engine, 304k, daily driver
'06 S60 R, 201k
'07 XC70, black, 205k
'07 XC70, willow green, 223k
gone: '96 NA 850 210k, '98 NA V70 182k, '98 S70 NA 225k, '96 855 NA 169k
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snugani
- Posts: 24
- Joined: 30 Jun 2023, 15:44
- Year and Model: 1996 855 turbo
- Location: The Garden State
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So I checked closer and you were right. A small portion of the wiring right before going into the female bullet connector is broken. I’m going to try and get some new bullet connectors and crimp them on as a temp fix. I believe the wires are 18 gauge. Hopefully I’ll only have to trim a short length to get to good wire.
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RickHaleParker
- Posts: 7195
- Joined: 25 May 2015, 14:30
- Year and Model: See Signature below.
- Location: Kansas
- Has thanked: 8 times
- Been thanked: 977 times
Ohm meter is your friend right now. Even a cheap one.
Active
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2017 Ford PIU. 3.5l, Twin Turbo, 365 Hp.
............................
Past
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000. ( Killed by a plastic radiator. )
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion ( I moved, the project did not )
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0. ( Transmission dead after sitting for a winter )
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2017 Ford PIU. 3.5l, Twin Turbo, 365 Hp.
............................
Past
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000. ( Killed by a plastic radiator. )
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion ( I moved, the project did not )
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0. ( Transmission dead after sitting for a winter )
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