FickFab
Member
Resolved - Loose pin either A11 or A27 at the ECU plug. Tightened up both pins and the code has cleared!
Hello
We have decided to join the community in hopes of some assistance with a diagnosis for a machine we are working on. A customer purchased a mini jet boat that was made by another builder using a 2009 RXT 255 as the donor. The customer was experiencing some issues with the boat and wanting some parts added/built for it so it has come to my shop. We have been able to do everything the customer wanted except for one tricky code, P0118 engine overheat. So the customer said the boat would occasionally alarm with the overheat code and go into limp mode and he would shut it off and back on and some times it would clear, other times it would need to be limped back and would be fine the next time he tried it. When we received the boat here there was a 14 count for the P0118 code, and at the time it was inactive and we were able to clear it. Upon completing the other repairs and test firing the boat we had the P0118 code come back, and now it has been active ever since and can not be cleared. So we have started digging into diagnosing it and this is where we are hoping for some assistance.
P0118 - Engine temperature sensor voltage too high
- Engine overheated or damaged sensor
- Check for debris or blockage in cooling system. Check the sensor for approximately 2280 to 2736 ohms at 19 to 21°C (66 to 70°F). Check for approximately 2280 to 2736 ohms at 19 to 21°C (66 to 70°F) between ECM connector pins A-A1 and A-J2. Refer to the Service Manual for more details.
Although the code is always active, even when the motor is cold, we have ruled out as much as we can including things that shouldn't be of concern with an overheat code that is active when the motor is ice cold... The thermostat is functioning, the fresh water cooling is flowing well and plumbed properly, the glycol system is flowing and does not have trapped air. The customer had already replaced both the exhaust temp sensor and the engine temp sensor before bringing it to us but we checked everything there as well and both sensors are good, plugs are good, cleaned, and new dielectric grease, and wiring is good all the way back to the ECU plug. Resistance was checked at 3 different temperatures at both the sensor, and at the ECU plug and all is good and consistent. We have cleaned out the plugs at the sensors and at the ECU and applied new dielectric grease to no avail. So to us, this is indicative of a bad ECU, but I know in past experiences we had had strangely related items fix codes before and I am hopeful that there could be a weirdly related component that we have not looked at that could be causing this. For instance we have had a P0122 code (TAS throttle sensor) fixed by replacing the roll over protection valve on a 2010.. So if anyone has any suggestions on what we could look at before we replace the ECU that would be great as we would like to rule out absolutely everything before going the ECU route.
As a side note, we may be in the market for an ECU from a 2009 RXT 255 (2008 - 2011 RXT/RXP I believe are all the same) part # 420665861 if anyone has one available that is known to be a good working ECU. Ideally if anyone is local to the Vancouver, BC region with a 2008 - 2011 (not 100% sure on the years there) RXT/RXP 255 with the same ECU and would be willing to let us plug it into this motor to try and confirm a faulty ECU diagnosis that would be great!
Hello
We have decided to join the community in hopes of some assistance with a diagnosis for a machine we are working on. A customer purchased a mini jet boat that was made by another builder using a 2009 RXT 255 as the donor. The customer was experiencing some issues with the boat and wanting some parts added/built for it so it has come to my shop. We have been able to do everything the customer wanted except for one tricky code, P0118 engine overheat. So the customer said the boat would occasionally alarm with the overheat code and go into limp mode and he would shut it off and back on and some times it would clear, other times it would need to be limped back and would be fine the next time he tried it. When we received the boat here there was a 14 count for the P0118 code, and at the time it was inactive and we were able to clear it. Upon completing the other repairs and test firing the boat we had the P0118 code come back, and now it has been active ever since and can not be cleared. So we have started digging into diagnosing it and this is where we are hoping for some assistance.
P0118 - Engine temperature sensor voltage too high
- Engine overheated or damaged sensor
- Check for debris or blockage in cooling system. Check the sensor for approximately 2280 to 2736 ohms at 19 to 21°C (66 to 70°F). Check for approximately 2280 to 2736 ohms at 19 to 21°C (66 to 70°F) between ECM connector pins A-A1 and A-J2. Refer to the Service Manual for more details.
Although the code is always active, even when the motor is cold, we have ruled out as much as we can including things that shouldn't be of concern with an overheat code that is active when the motor is ice cold... The thermostat is functioning, the fresh water cooling is flowing well and plumbed properly, the glycol system is flowing and does not have trapped air. The customer had already replaced both the exhaust temp sensor and the engine temp sensor before bringing it to us but we checked everything there as well and both sensors are good, plugs are good, cleaned, and new dielectric grease, and wiring is good all the way back to the ECU plug. Resistance was checked at 3 different temperatures at both the sensor, and at the ECU plug and all is good and consistent. We have cleaned out the plugs at the sensors and at the ECU and applied new dielectric grease to no avail. So to us, this is indicative of a bad ECU, but I know in past experiences we had had strangely related items fix codes before and I am hopeful that there could be a weirdly related component that we have not looked at that could be causing this. For instance we have had a P0122 code (TAS throttle sensor) fixed by replacing the roll over protection valve on a 2010.. So if anyone has any suggestions on what we could look at before we replace the ECU that would be great as we would like to rule out absolutely everything before going the ECU route.
As a side note, we may be in the market for an ECU from a 2009 RXT 255 (2008 - 2011 RXT/RXP I believe are all the same) part # 420665861 if anyone has one available that is known to be a good working ECU. Ideally if anyone is local to the Vancouver, BC region with a 2008 - 2011 (not 100% sure on the years there) RXT/RXP 255 with the same ECU and would be willing to let us plug it into this motor to try and confirm a faulty ECU diagnosis that would be great!
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