Flushing coolant when replacing thermostat and temperature sensor

Tiny
BRENTULRICH88
  • MEMBER
  • 2009 DODGE CARAVAN
  • 3.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 164,000 MILES
Hello,

I recently had my radiator replaced and fresh coolant put in. Unfortunately my van kicked a P2181 code intermittently before and after the radiator was replaced. I should have replaced the thermostat and temperature sensor before the radiator was replaced but you live and learn I guess. So my question is, is it absolutely necessary to do a coolant flush? I know I will lose coolant when replacing the thermostat and temp sensor, but trying to avoid a flush seeing how fresh coolant was just put in.

Also,

Is it okay to put my van on vehicle ramps if I need to flush the coolant?


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Thursday, July 11th, 2019 AT 5:28 AM

16 Replies

Tiny
SCWICKEDSTANG
  • EXPERT
Hello,

A coolant flush is a good idea because it will knock out any debris and gunk you have in your cooling system. This includes your engine block and cylinder head(s). Debris can collect over time and when it breaks free it can clog radiator/heater core fins, cause a thermostat to stick, etc. So I would recommend doing it. It only takes 15 minutes or so to do, but the decision, of course, is yours. Putting your vehicle on ramps is okay to do cooling system work. Make sure it is in park and the emergency brake is set, and/or wheels are chalcked. Always think safety when working on a vehicle. Please get back to us with how things turn out.

Thanks,
Alex
2CarPros
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Thursday, July 11th, 2019 AT 5:53 AM
Tiny
ASEMASTER6371
  • EXPERT
Good morning,

If you flushed it already, you need not due to do it a second time.

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

Just drain the coolant into a clean pan and reuse it when you replace your parts.

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Yes to the ramps. Makes it easier.

Can you verify the code? There is no 2181 code.

Roy
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Thursday, July 11th, 2019 AT 5:54 AM
Tiny
BRENTULRICH88
  • MEMBER
https://www.google.com/amp/s/www.autocodes.com/amp/codes/p2181_dodge.html

Here is the code.

Thanks
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Thursday, July 11th, 2019 AT 6:01 AM
Tiny
ASEMASTER6371
  • EXPERT
Okay, that's a general code for Dodge but it is not specifically for your van.

Did you have the code read with a scan tool?

Roy
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Thursday, July 11th, 2019 AT 6:10 AM
Tiny
BRENTULRICH88
  • MEMBER
Yep, went to an auto parts store and it said engine cooling performance. Is that what you are looking for?
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Thursday, July 11th, 2019 AT 6:12 AM
Tiny
ASEMASTER6371
  • EXPERT
Was the code from the parts store the 2181 or was it a 128?

Roy
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Thursday, July 11th, 2019 AT 6:22 AM
Tiny
BRENTULRICH88
  • MEMBER
P2181.
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Thursday, July 11th, 2019 AT 6:23 AM
Tiny
ASEMASTER6371
  • EXPERT
Can I have the complete VIN number?

Roy
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Thursday, July 11th, 2019 AT 6:25 AM
Tiny
BRENTULRICH88
  • MEMBER
1D8HN44E89B502548
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Thursday, July 11th, 2019 AT 7:19 AM
Tiny
ASEMASTER6371
  • EXPERT
Okay, possible issues.

What is the voltage at the coolant sensor engine off, key on?

Roy

P2181
Descriptor
Cooling System Performance
Probable Causes
Engine Coolant Level and Condition
Engine Coolant Temperature (ECT) Sensor
Engine Coolant Temperature (ECT) Sensor Signal Circuit High Resistance
Engine Coolant Temperature (ECT) Sensor Wiring or Connectors
Powertrain Control Module (PCM)
Sensor Ground Circuit High Resistance
Thermostat

Flow chart

- Set Condition:
The ECT sensor voltage should only change at a certain rate. If this rate is too slow or too fast, this fault will set. Two trip fault. Three good trips to clear MIL. ETC light will illuminate on first trip failure.

ImageOpen In New TabZoom/Print

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. See: Computers and Control Systems > Initial Inspection and Diagnostic Overview > Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC

NOTE: Improper installation of a block heater could cause this DTC to set.

NOTE: Review Freeze Frame data. Extremely cold ambient temperatures may cause this DTC to set.

NOTE: Diagnose and repair any ECT sensor circuit or temperature sensor performance DTCs before continuing with this test.

NOTE: Inspect the cooling system for any conditions that can cause a change in engine warm up time, such as a broken water pump impeller or the addition of an aftermarket auxiliary cooler.

1. Turn the ignition on.
2. With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

- Refer to the CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. See: Computers and Control Systems > Initial Inspection and Diagnostic Overview > Checking for an Intermittent DTC.

2. CHECKING THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION
1. Perform the diagnostic procedure for CHECKING THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION. See: Computers and Control Systems > Component Tests and General Diagnostics > Checking the Engine Coolant Temperature Sensor Operation.

Were any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. See: A L L Diagnostic Trouble Codes ( DTC ) > Verification Tests > PCM Verification Test

No

- Perform the POWERTRAIN VERIFICATION TEST.. See: A L L Diagnostic Trouble Codes ( DTC ) > Verification Tests > PCM Verification Test
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Thursday, July 11th, 2019 AT 7:33 AM
Tiny
BRENTULRICH88
  • MEMBER
So I already have the thermostat and the temperature sensor. I was going to replace those since I have them. If that is the problem will/should the check engine light clear? Or may it take a little bit? Also, I am trying to see how much coolant should be in my van? Should I fill to top of the radiator, then put in the correct amount in the reservoir? The capacity states 13.4 quarts which is a little over 3 gallons. That seems like a lot?
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Thursday, July 11th, 2019 AT 7:40 AM
Tiny
ASEMASTER6371
  • EXPERT
If you do not clear the code, it will clear itself after 50 key starts with no failure.

2 gallons is good. The other figure is for a completely dry system.

Roy
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Thursday, July 11th, 2019 AT 7:46 AM
Tiny
BRENTULRICH88
  • MEMBER
Okay, I will let you know how things turn out. Thanks for your help.

Thanks
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Thursday, July 11th, 2019 AT 7:47 AM
Tiny
ASEMASTER6371
  • EXPERT
You are welcome.

Always glad to help.

Roy
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Thursday, July 11th, 2019 AT 8:23 AM
Tiny
BRENTULRICH88
  • MEMBER
I forgot to ask. Will I need a 3/4 deep well socket to replace the temperature sensor?
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Friday, July 12th, 2019 AT 5:48 AM
Tiny
ASEMASTER6371
  • EXPERT
Correct.

Roy
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Friday, July 12th, 2019 AT 5:54 AM

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