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No wiring to be found for coolant temp sensor on '98 2.8 v6 Audi

My gauge cluster shows the water temp maxxed out and the overheating warning light is always on, but the car is not overheating. Found the sensor in the lower radiator hose on the pass side has nothing plugged into it and I cannot find the wire with plug to hook it up anywhere. I've been looking for hours at every inch of the engine bay and there are no unplugged wires hanging anywhere. At this point I have no idea what to do next. Any advice would be great.

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What i would guess it that the person before you had the car, left the plugs off from the sensot, and they melted onto something that got very hot. That would explain why it would read overheating. Check everywhere near the sensor for places it could have melted onto and then either buy a new plug for it, or just soder the wires straight onto the sensor.(Not reccomended )

Posted on Jan 08, 2009


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Posted on Jan 02, 2017


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Engine temp gauge not reading and ac will not turn on due to engine hot warning, diognostics say its a sensor, need to know which one and can i do it myself?2003 saturn vue

What diognostics say its a sensor ?????? No diagnostic's ever tell's you it's a sensor . You as a technician would need to prove that by testing electrical circuits , viewing coolant temp sensor . Hooking scan tool and trying to command the gauge with by directional control . The temp gauge not showing any temp. ? No movement ? Engine Coolant Temperature Gage Inaccurate or InoperativeStep Action
Schematic Reference: Instrument Cluster Schematics
Did you perform the Instrument Cluster Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - Instrument Cluster
Install a scan tool.
Turn the ignition ON, with the engine OFF.
With the scan tool, perform the Lamp and Gauge Check in the IPC Special Functions list.
Does the engine coolant temperature gage move up and down when commanded?
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
Go to Step 3
Replace the IPC. Refer to Instrument Cluster Replacement .
Did you complete the replacement?
Go to Step 4
Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 2
Would hate for you to replace the coolant temp sensor an find out that's not the problem ! Does the vehicle start an run good ,trans mission shift good ? If so it's not the coolant temp sensor .
Engine Coolant Temperature Gage
The ECM sends coolant temperature as determined by the coolant temperature sensor to the BCM via CAN serial data. The IPC displays the engine coolant temperature with the gage when the BCM sends a class 2 message to the IPC indicating coolant temperature percentage. The engine coolant temperature gage defaults to cold (0°) or below if:
• The ECM detects a malfunction in the engine coolant temperature sensor circuit.
• The IPC detects a loss of class 2 communications with the BCM.
• The BCM detects a loss of CAN communications with the ECM.

Aug 19, 2017 | AC Cars & Trucks

1 Answer

Does the 98 Ford F-150 5.4 triton have two coolant sending units? I found the one on the intake and replaced it and still no gauge.

Has CHT - cylinder head temp. sensor . This sensor is a input to the PCM - engine computer . The PCM sends engine temp info on serial data network to the instrument cluster . I/C has a microprocessor inside . Have it check for DTC'S - diagnostic trouble codes . Not OBD2 codes , B - body codes . The gauge could be the problem , which means replacing the instrument cluster .
Engine coolant temperature information is received by the instrument cluster from the PCM over the SCP network. Temperatures over 121°C (275°F) will display hot (H). If the engine coolant temperature data is missing or invalid for five seconds, the instrument cluster will move the engine coolant temperature gauge below the cold (C) position.
The best way to diagnose this is with a scan tool , factory or a professional type . Know how the system works and not replacing parts is the proper way to diagnose .
U1073 D073 SCP (J1850) Invalid or Missing Data for Engine Coolant PCM CARRY OUT the PCM self-test.
  • A single gauge does not return to zero with the ignition switch off
  • Instrument cluster.
  • INSTALL a new instrument cluster; REFER to Instrument Cluster . TEST the system for normal operation.

  • Incorrect temperature gauge indication
  • Circuitry.
  • Instrument cluster.
  • PCM.
  • Engine coolant temperature sensor.
  • GO to Pinpoint Test F .

I should also point out that if the temp sensor were bad the vehicle may not run right .
Using the factory scan tool
Trigger instrument cluster active command ENGCOOLNT. Monitor the engine coolant temperature gauge while adjusting the ENGCOOLNT active command to read 50% and 100%.
  • Does the temperature gauge start at cold, move to half at 50%, and full hot at 100%?
Yes REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.

No INSTALL a new instrument cluster; REFER to Instrument Cluster . REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
Your best bet , take it to a qualified repair shop !

May 29, 2017 | Ford Cars & Trucks

1 Answer

Temperature gauge for kia 2002 v6 is not working,the car drives ok not overheating

Either your coolant temp sensor is bad, or the wiring going to the temp sensor is faulty. Also, check your thermostat and your fluid levels. My bet would be on the coolant temp sensor though.

May 07, 2017 | Kia Cars & Trucks

1 Answer

The light is flashing on the top left of the 4 squares. Its 1996 Audi A4 1.8 auto. What does it mean

Is this you instrument cluster? vtraudt image
If so, top left would be coolant temperature warning light.

What is the coolant temp gauge reading?

I would suspect faulty coolant temp sensor.
Also check if your coolant reservoir sensor (plugged into the bottom of you coolant tank) is plugged in (I often forget to plug it back in; the retainer also easily breaks and the plug can slip out).

Jan 28, 2015 | 1996 Audi A4

2 Answers

Where is the coolant temp sensor on a suzuki grand vitara

If it's a 2.0 it'll be on the back of the cylinder head on the intake side, sort of between the engine and the firewall - it is a single unit with two separate and independent sensors, one for the dash guage, the other for the ECU.


Aug 26, 2012 | Suzuki Grand Vitara Cars & Trucks

2 Answers

Temp gauge on hot even though car is not overheating

Have you checked the temp sensor ? It could be faulty or there could be a wiring problem back to the gauge. Low coolant can cause an air pocket inside the system too.

Jan 04, 2012 | Cars & Trucks

1 Answer

My temp. gauge is sporatic. Sometimes starts in middle then guickly jumps way past hot mark to pointing straight down. But car is not overheating. Any thoughts?

There are two things that would cause this a bad coolant temp sensor or the guage is bad, this cars had alot of problem with the cluster, the gauges would do crazy things the most common would be the fuel gauge and temp gauge, i would start by replacing the coolant temp sensor and making sure the wiring to sensor is good and not frayed and touch any metal, hope this is helpful.

Oct 31, 2010 | 2004 Chevrolet Impala

2 Answers

Silverado Coolant not getting hot enough?

it has to be either a broken gauge, faulty wiring, or poor coolant flow (although in the summer i doubt the coolant is staying 'too cold' in reality).
First, we will check the temp sensor 1. Pull the temp sensor out and let it hang. 2. Boil water -- it will be at 212* at its boiling point but cooling rapidly, so speed is key. Or better yet, if you have a thermometer and vegetable oil and steady hands, heat that up to 250* 3. Take the water or oil to the sensor and pop the sensor in it. Watch the gauge to see if it reads accurately (should show around 200 if you moved quickly with the water, oil will still be ~240ish and will work better, but is more dangerous). If the gauge is off, then we've found the problem. For better measure, if you have a thermometer you can place that next to the temp sensor to compare results.
if the temp reading is too low (lower than what your thermometer reads), it is also possible that you have a short in the wiring or simply corroded wires connected to it, adding resistance to the wire which would result in a lower reading. (people sometimes use this to their advantage with the air temp sensor -- add a 100ohm or so resistor in-line with the sensor to trick the cpu into thinking the temp is colder, prompting it to adjust the air/gas mix and yielding a couple hp increase, although damaging to your system.)
the more i think about it, the more a faulty wiring feels like it could be the problem. if the temperature is reading accurately, i'd take a serious look at the flow of coolant through the system. if it isn't heating up then it must not be contacting enough heat. there may be blockage somewhere; crimped hose or maybe just mystery gunk.
hopefully this helps, if anything it's a start. most of the time it seems like solutions are found unexpectedly when testing completely different things. good luck!

Jul 14, 2009 | Chevrolet Silverado 1500 Cars & Trucks

3 Answers

Audi A4 2.5 V6 TDI - Creamy grey coolant in expansion tank

Sounds like blown head gasket (or worse) still to me.
Remove oil filler cap and look for grey oil.
Never use water these days but special coolant. Water makes vapour spots and cause block cracks, worse then blown gaskets!!!
vapour does not cool very well.
Look like you have cracks already.
Take a compression test if possible. But might not show op at that temperature.
The gauge indication troubles me.

Apr 14, 2009 | 1998 Audi A4

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