Hello,I have a bad temperature sender on the port side of my engine. At least that is what the computer tells me. It gives code 41 and 42. Temperature sender on the port side below minimum spec. or that the wiring shortcircuits somewhere.Even when the engine is not running the check engine light is on.How is it possible that when I disconnect the temperature sender the fault code remains?HELP !!!
The sensor uses a 5 volt reference signal. The sensor is basically a variable resistor. Temperature changes the resistance and as the resistance changes the reference voltage changes.When you disconnect the sensor (open circuit), you cause the code 41. Because there's no return voltage, the code 42 activates (the computer reads it as temperature below range).Replace the sensor.-John
Thanks John !! I will replace it.I have a sparkplug related problem to this issue. A new set was fouled in only one hour when I went out with the check engine light on.Can you tell me how this works? After I have cleaned the plugs and replaced the temp sensor, everything should be back to normal?
John,It is a fuel related carboning I think, black color, not sticky.Can I ask you about the 5 volt reference signal? Mine only gets 5 mV (0,005 Volt) [Engine not running]. Should the engine run before it gives 5 v??
If the engine is not running cylinders on that bank it will give you a cold code. Check the engine first. Start with the spark plugs. You maybe chasing a run problem thinking its a sensor problem. When the sensors are doing there job.
Hello Vinney,After cleaning the plugs the engine runs fine at full performance for approx. one hour. After that it starts to mis on one of the cilinders. I wouldn't get full performance when not all the cilinders where working. I would notice that I think. Can't it be the other way around?. The engine gives code 41 and 42. Temperature meter malfunction. Then the EMM ignores the actual value and starts adjusting the fuel/air mix. I think that results in my problem?I will re-index the plugs today and try again. What is your opinion on my check engine codes?
That's incorrect Vinnie. Regardless of whether or not the engine is running, the temp sensors temperature reading is normally within a few degrees of the ambient temperature.Code 41 is the temp sensor open circuit code. Either the sensor has failed (open), or there is a wiring harness issue between the sensor and the EMM, it could also be an EMM problem, but that doesn't seem to be the case as yet. The sensor should ohm out at 9000 to 11000 ohms at 77F degrees (25C).Code 42 is telling you the EMM senses the temperature is below the expected range, the low limit being 14F (-10C). In your case, this is most likely because of the sensor's open circuit. The EMM will allow the engine to run, but it will be in continuous warm-up mode, because it cannot read a temperature change. The EMM will supply extra fuel until the engine finally warms up. This could be part or all of your problem. Were you experiencing plug fouling problems before the sensor failure? If yes, them something else could be going on too. Have you noticed any smoking at start up or extremely fast idle rpm at start up?The 5 volt reference circuit voltage must be monitored with the diagnostic progam. Are you trying to monitor voltage with a volt meter? Or is your reading from the diagnostic program?-John
Hello John,In am trying to read it with the volt meter and not with the diagnostic program. The resistance on the temp sensor checkes out at approx 10.000 ohms. When I heat it up in a bowl of water it goes down to approx 2.000 Ohms.I did not notice any smoking at start or fast idle up and I never experienced any problems before. Alle the problems started with the check engine sign. The boat ran fine at high speeds.I did notice when the check engine light comes on (and the wiring has an open or sensor failure) the rpm goes up +200 rpm and in neutral the rpm raises up and down. I can simulate this when my temp sensor is working (he doesn't always seems to fail) and disconnect it. Then I get the same symptons.One day one of my plugs went bad and I replaced the whole set. I indexed them, gapped them as described at boatsetup.com. After that my plugs were OK for one hour and then the "missing" problems began. I can hear that one of the cilinders/plugs is trying real hard to do its job, but it can't (due to plug fouling??). I can hear it come and then it misses again.I again re-indexed, re-gapped and cleaned the plugs and the engine ran fine again. For one hour and then the problem with one or two of the plugs beginning to miss again. Today I measured the voltage of the temp sensor on a 50 E-tec engine as a reference. It gave me a 2.7 volt on the volt meter. My engine gives 0,005 volt when not running. That is a big difference and has made me worry about my EMM.My engine has only 112 hours on it.
To all who read this:The problem turned out to be EMM related. There was an internal open. I sent it to DFI electronics. I am currently awaiting the rebuild EMM. The problems should be over now, so I can be BOATING !! again. John and Vinney: thanks for all the help. Greatly appreciated.