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Civic - Engine D14A2 - Gauge Temperature Issue

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Hello guys,
I'm new user from Italy (sorry for bad English).
I need help to understand what is happening on my mother's car, 138.000 km engine model D14A2
Some issues started after a routine maintenance on the engine; engine head, cam belt and water pump have been changed. If I am not wrong these components are all exchanged during this checks.

After many km (don't know exactly how many) the engine were not able to keep reach and maintain the normal temperature because of an issue with the thermostat (in fact petrol consumption was anomalous). The mechanic changed the thermostat and a new issue has appeared immediately. The temp gauge begun to failed to measure the correct engine temperature. The gauge was moving up to 1/4 of the gauge scale instead of moving just before half scale.

I took the car back to the mechanic but he wasn't able to fix the issue. He checked the engine and said that it was ok. He told me to do not worry about a false reading.
At that moment I understood that he was not able to fix it (or maybe he didn't want to spent time on an old car and moving on other cars more profitable) and I thought to fix by myself the issue and also
save money from that mechanic (which caused more issue then fixes).

I made many searches on internet to fix the issue by myself.
First I replaced the ECT sensor (the one with the o-ring) but unfortunately the issue was still there.
Then I checked the ECT gauge sending unit (by following the instruction from the Honda service manual); I put to ground the yellow green wire that connects the sensor to the gauge and turned on the car switch to position III. The gauge started to move to the H mark very fast. I turned off the switch before it were going to reach the H mark (as the manual warned). That allowed me to check if the issue was on the gauge itself or on the sensor.

So I decided to buy another ECT gauge sending unit. I bought the replacement part directly from Honda (80 euros); then I mounted it on the car. The original component has been broken during the disassembly.

Unfortunately the issue is still there but (and this is what is also makes me even more crazy) now the gauge reads an higher engine temperature; in fact it goes up around 3/4 the scale.
Anyway the engine temperature is ok; in fact the pipeline from the radiator to the engine can be touched with the hands when the engine is on and the radiator fan does not turn on in normal condition. I haven't checked yet if it start turn on under workloads but I think it works.
Coolant level seems ok to me.
So... any suggestions on how to fix the issue???
Please help me!!!


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  • MummysCar changed the title to Civic - Engine D14A2 - Gauge Temperature Issue

Could be a number of things but two that I would check are the following:

  • Air lock in the coolant system.
  • Thermostat

The airlock is the first to check as this doesn't cost anything. You need to make sure the coolant system has been properly bled after the head/water pump was changed. Does the heater give good heat when turned onto hot? Does it maintain good heat when turned to hot, even when on the move?


The thermostat can be problematic. I have seen even brand new ones that are faulty It may be worth swapping it to see if another resolves the issue.


Can I ask why the head was changed in the first place? These D series engines are not known for blowing head gaskets so be interested to hear why the garage/mechanic replaced it. Were the head/block checked before a new gasket was fitted? Did the car have any temp issues before the mechanic worked on the car?


I would deffo check the cooling fans are kicking in. Leave the car stationary and ticking over, the fan should come on after around 5 to 10 mins, depending on the outside temp. If it doesn't come on you need to test the fan is actually working, if it is then next check would be the sensor for it. Last thing you want is the fan not to kick ion and the car overheating.


The D series engines are pretty bulletproof so hopefully whatever the fault is it should be easy to fix.


Let us know how you get on

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Hello Dave,
thanks for your fast reply :)
I will definitely do your checks. But please wait a bit. I am pretty busy every day so it will take time.
The car has always been in perfect condition. No previous issues were known before doing that big maintenance on the car.
I don't know if the head was checked before the new gasket was fitted (I think yes, see below)

In the meantime I would have a clarification.
What do you mean with "the airlock"? Do you mean a bubble inside the coolant circuit?
I unscrewed a bit the radiator cap with the engine on normal working temperature and some coolant has gone out. I think there is no bubble inside. Anyway I can redo the same test if you think it needs to be done again.
Tomorrow I'm going to check if the the heater gives a good heat inside the c**kpit and if I have enough time I will try to check if the radiator fan kicks in by put on ground the wire; that's because now is really cold and is hard to makes the engine reach a temperature beyond the 100C

Last but not least I have retrieved the invoice which list what components have been changed (note: I have used an online translator); the components that have been changed are:

item codes and description from google (not sure if I can post links. Feel free to delete them)

5232xs - TIMING BELT - https://www.fabioizzoautoricambi.it/cinghia-distribuzione/1518-94158-5232xs-cinghia-distribuzione-honda-civic-cassa-77a-disponibile-gates-3-pz-5412571007237.html

03130 - (not sure in English -> tensioner bearing distribution

4pk795  belt - not further description

4pk812  belt - not further description

4pk788  belt - not further description

428pa - water pump

and coolant liquid

About engine head/head gaskets.. it has not been replaced (the invoice does not have anything related to). Anyway I remember that the mechanic said something about the head. Maybe they have dismounted it to perform other jobs like changing the belts?

Thanks again David,
have a good day

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