2005 civic. Starts and runs well. But once engine has been on a while and then turned off. It is hard to restart. I recently to placed to Crank sensor. Engine light is on, code says O2 sensor bank 1. I replaced the ignition relay. Just To see if that was the issue. The car sits


a lot. Used once in a while. I didn’t have this issue before the replacement of the sensor. Do you think that I just got a bad sensor?Or the o2 sensor would case this? I was thinking maybe the fuel pump since it sits for long periods. Maybe once fuel pump is hot. It stops sending fuel. It will crank just not fire up after it’s been running for a while. Anyone have this problem before? Thanks for all your help and input. Angel186

 

Sounds like the replacement cam sensor is not working when hot??

ECM uses cam sensor to time the engine and know when to give it fuel and spark
If faulty then the engine will not start (at any time the cam sensor is faulty)

When engine is cold, ECM uses a fuel map during open loop
When engine is warmed and system goes into closed loop, the ECM uses the up stream O2 sensor to adjust air/fuel mixture
If faulty then possible it will prevent engine from starting when warm

Fuel pump sits in gasoline, the gasoline keeps the fuel pump cool
It is rare that a fuel pump would fail in this particular way.
Unless you tend to drive the gas tank into empty most times
But, if you listen carefully then when you turn key to the "ON" position
Should be able to hear the fuel pump prime fuel rail for about two seconds

A fuel injector that is leaky will dump fuel into the cylinder
And wash the cylinder of the oils it needs to make a seal for compression
Besides the cylinder wash, it can flood the engine which makes for hard starts.
Push gas pedal all the way to floor and crank engine for about five seconds
This is called clear flood mode. Then try to start engine as normal.

 

Thank you for your input. I edited my post, I changed the crank sensor. Not the cam sensor. I’m guess you are right that I have a bad sensor. I did get the part from Oriellys. I just may need to get the crank sensor from the dealer. Or find a better brand.the engine light is on at this time but the O2 code is the only thing showing at this time.

 

The O2 sensor code is for the heater circuit.
Either the heater is shorted or the heater is opened.
Inspect the wiring to make sure no short, fray, etc
Can also put an ohm meter on heater circuit.
Usually they are the same color.

As for the no start when hot, you can check to see if there is injector pulse or spark??

 

With the engine is hot. I do not believe it is getting any spark. I checked the ignition relay and it checks out to be good. With me getting no spark, does that mean that the crank sensor is bad? When I drove it the other day I turned on the air condition and it was only giving me hot air.Does that have something to do with the O2 sensor being open as you said.?

 

The AC is a separate system.

When there is no spark and no injector pulse, the crank sensor would be suspect
The crank sensor tells the ECM that the engine is rotating.
If the rotation stops for any reason then the ECM shuts down the fuel pump, spark to plugs and fuel injectors
This is in case there was something to cause the engine to stop, for example: an accident.
You don't want the fuel pump running and the spark plugs going if there is a spill of any sort.
So, it is possible that the new crank sensor is causing the no start when hot.
You can get cold spray (electronics stores use to have them) and use it in the vicinity of the crank sensor when it is hot and won't start
If the engine subsequently starts then crank sensor is probably bad when hot.

Note: Have heard of the main relay having cold solder joints that cause no starts.
Good luck troubleshooting


Here is another possible cause. Engine coolant temperature sensor.

 

This is definitely a really weird issue. However, it seems that the cam sensor you are using as a replacement doesn't work properly when it's hot