Could a faulty ECT sensor cause the car not to start?
 

the car sometimes takes a while to start, everything turns over. new battery,alt,starter,fuel pump. went to my friends house to get it scanned and it said the coolant temp sensor. would that really be the problem? and should i replace the thermostat also? thanks

re: Could a faulty ECT sensor cause the car not to start?
 

ECT would let ur car start, but would hesitate big time... almost like it's misfiring for a while til it warms up. thermostat doesn't have anything to do with ect. so is it cranking for a while then starts and runs fine? or does it crank over, run like arse, and then after a lil while it runs better?

re: Could a faulty ECT sensor cause the car not to start?
 

it cranks then starts after a while...everything turns over fine.

re: Could a faulty ECT sensor cause the car not to start?
 

runs fine, just takes a while to start

re: Could a faulty ECT sensor cause the car not to start?
 

generally speaking when the ECT is bad enough to keep the car from starting it has a serious driveability issue because its usually running pig rich. I suspect multiple issues. How long has the CEL been on?

re: Could a faulty ECT sensor cause the car not to start?
 

at times i've had issues with my civic not starting easily. it's normally when it sits for awhile and hasn't been run for about 8+ days. i've checked the CEL's and the Coolant Temperature Sensor code flashes. when the engine finally starts the CEL stays on for a little while and it also runs real rough. i have to let it warm up for a few minutes before trying to drive it. otherwise it stumbles and misses, and normally stalls out. when the car sits for awhile not being driven, and i first turn the key the CEL normally stays on due to the Coolant Temperature Sensor. starting the engine is extremely difficult. when the engine finally cranks over the CEL sometimes stays on until the car warms up enough and i shut it off and restart it. seems like your engine has a similar issue, though it could be 2 or more issues with sensors. not just the coolant sensor. every engine/car/setup has a mind of it's own. LOL hope you work out the issues soon!

re: Could a faulty ECT sensor cause the car not to start?
 

The coolant temp sensor will not keep the car from starting...period. The parameters controlled by the ECT in the management are tiny. Only very small amounts of fuel and ignition compensation occur, not nearly enough to cause a no start.

Hard to start issues could be as basic as simple "tune-up" items, ignition timing, or idle control system components. Start simple and move from there. Of course, replace the ECT simply because it's bad or you have a wiring issue.

re: Could a faulty ECT sensor cause the car not to start?
 

Actually, according to tech2tech.net (not up anymore), there is a no-start condition refered to as "Hot Soak Restart" caused by the TW sensor.

A warm engine receives too much fuel and floods out.

re: Could a faulty ECT sensor cause the car not to start?
 

sorry man thats wrong, I have diagnosed several cars (different makes and models) that have a had a no/hard start because of ECTs. IF and when they do start they run like complete shit and billow black clouds of smoke.

re: Could a faulty ECT sensor cause the car not to start?
 

I second that as someone who has been a diagnostic tech for over 20 years. Some models as more affected than others by an open CTS.

re: Could a faulty ECT sensor cause the car not to start?
 

Maybe you think that's what you diagnosed, but an ECT malfunction has nowhere NEAR the parameter range available to be billowing smoke...nowhere NEAR. I'm not speaking for other makes and models, I'm telling you in terms of Honda Civic, period.

I'm not going to argue here. Everyone at a Honda dealership or wherever blabs about their decades of wisdom. I've got my own decade and a half and speaking in terms of OBD1 Honda, ECT isn't creating a no start.

Looking closer at the OP's avatar I see an OBD2 ass, so maybe in terms of OBD2 a hard start is quite possible, but not a no start if that's the only issue.


Point is OP, replace or repair the ECT. No one is disputing that. Assess the situation from that point, then begin troubleshooting further. For the vehicle to run perfectly it needs no fault codes first and foremost, so take what the ecu has handed you and fix it.

re: Could a faulty ECT sensor cause the car not to start?
 

Diagnosis tough without more history on similar Ridgelines/Honda 3.5 V 6's. I have replaced both relays that affect fuel ignition? I have replaced the notorious PGMFI (blue) and another troubled relay (brown) that is named: Fuel Injection Relay -- Computer Control? No change, so now I question: Is there any reason to believe that engine coolant temp sensor (ECT) is keeping truck from starting? Problem is worst when weather is hot and /or when engine is hot and short runs. Are there other temperature sensors with parameters (amounts of fuel and ignition compensation) in the engine control management that could be causing hard starting, but smooth running after start?

Engine temp sensor(s) with parameters that may be causing hard starting?

re: Could a faulty ECT sensor cause the car not to start?
 

Having the same issue. When its cold is hard to start. But it doesn't do it at all time every once in a while. But once is on its smooth.

re: Could a faulty ECT sensor cause the car not to start?
 

Test the coolant temperature sensor. Should be 180-300 ohms when completely warmed up.

What happens is when these go bad they either cause the car to not get enough fuel when starting when cold - to getting too much fuel when the car is hot.

What's supposed to happen when the car is completely cold is that the ect tells the computer to inject more fuel. When it does this on a warm startup the car has too much fuel to handle. That's why when you start it in that particular situation it shoots out black fuel smoke. This isn't good on your spark plugs and catalytic converter too.

re: Could a faulty ECT sensor cause the car not to start?
 

Actually it will. I literally spent months trying to figure out the hard starting surging idle problem I had. I started with the fitv. Didnt work. Replaced the iac valve, still hard to start and surging... was told to replace the distributor because the distributor can cause the surge of the internals are bad....didnt work. Did a complete tune up and flushed the coolant. Even put in a new fuel pump. Actually got harder to start and timing was showing to be off, advancing way to much. I changed the fuel pressure regulator and nothing. I changed the back ect and it stopped starting. Just cranked and sometimes sputtered like it wanted to start. I changed the ect on the water outlet housing for the fans and my car started right up... I haven't had a starting issue since then so. You are incorrect. I was incorrect to because I thought it wouldnt cause a no start....but once I changed the front ect. It started in seconds.

re: Could a faulty ECT sensor cause the car not to start?
 

Two things:

1. This thread is 10 years old. The guy you're responding to may be long gone.

2. He was woefully wrong and dismissed professional experience as irrelevant, and instead, ironically, inserted his own limited experience as the prevailing insight to the subject matter.


His theory was incorrect and actually backwards. The ECT sensor in OBD1 vehicles had major authority over fuel control. In fact it was one of the primary inputs to injector pulse-width modulation.

Later,during OBD2(a little later than the beginning,say around 1999 or so) the ECT sensor was reduced to nothing more than an input sensor and held virtually no authority over fuel control. If the sensors reading were determined to be implausible by the ECM, the sensor was simply ignored, the CEL would come on and the vehicle would start and run like normal.