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| Engine fault light https://ukbeg.com/forum/viewtopic.php?f=8&t=15625 |
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| Author: | banjo1t [ 05 Oct 2012 15:48 ] |
| Post subject: | Engine fault light |
Hi Guys, My 1125r has developed a fault. After starting up and just after the cold light goes out (2/3 mins), the engine light comes on, and stays on, with the following... REAR 02 SYS ERR This message goes off after 3 secs and returns to GEAR etc; The bike runs, but can suddenly cut off without warning?? usually at low revs... Any ideas? Thanks in advance |
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| Author: | kevmean [ 05 Oct 2012 18:21 ] |
| Post subject: | Re: Engine fault light |
If the wires on the O2 sensors are the same length swap the front and rear sensors over and see if the fault swaps to the front ............... if it does it confirms the sensor is toast. |
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| Author: | banjo1t [ 05 Oct 2012 18:28 ] |
| Post subject: | Re: Engine fault light |
kevmean wrote: If the wires on the O2 sensors are the same length swap the front and rear sensors over and see if the fault swaps to the front ............... if it does it confirms the sensor is toast. Sorry for being a bit green! but does this mean oxygen sensor in the air intakes? |
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| Author: | kevmean [ 05 Oct 2012 18:32 ] |
| Post subject: | Re: Engine fault light |
banjo1t wrote: kevmean wrote: If the wires on the O2 sensors are the same length swap the front and rear sensors over and see if the fault swaps to the front ............... if it does it confirms the sensor is toast. Sorry for being a bit green! but does this mean oxygen sensor in the air intakes? No ........it's the sensors in the exhaust headers. |
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| Author: | banjo1t [ 07 Oct 2012 20:40 ] |
| Post subject: | Re: Engine fault light |
OK, I have managed to remove the rear sensor, I was unable to try to swap the wires without a major strip down, I have measured the resistance across the terminal to it's earth using an ohmmeter, and I get zero readings even at a 1000 ohm's. I reckon this is a duff sensor, what do you think anyone? |
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| Author: | pash [ 07 Oct 2012 21:10 ] |
| Post subject: | Re: Engine fault light |
The sensor doesn't work like that, it is essentially a fuel cell, it contains a catalyst that helps any unburned hydrocarbons turn themselves into CO2 and H2O and in doing so create a Voltage output. You get just under 1V when you run richer than stoichimetric, and 0V when you run leaner than stoihiometric. Bottom line is that a resistance test is not going to show if it works. I think you are looking at a harness or connector fault rather than a sensor fault. Sensors do fail, but chaffed wires and corroded contacts are more common. I would check resistance from the O2 sensor connector to the ECM plug as a starter. I would also check the state of the connectors and the harness. If that didn't show anything I would swap the sensor out (borrowing one if I could). |
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| Author: | banjo1t [ 07 Oct 2012 22:09 ] |
| Post subject: | Re: Engine fault light |
OK thanks Proff!! Will do a more detailed check/test of the wiring harness, and will report back..... PS may take a couple of days, as loads of other menial home tasks to do!! |
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| Author: | banjo1t [ 08 Oct 2012 20:57 ] |
| Post subject: | Re: Engine fault light |
OK, I have tested wiring from the rear 02 connector to the ECM and I am getting a full loop, so I can discount any fault in the wiring harness, without having a spare sensor, I may bite the bullet and buy one, have looked on ebay, and notice one is going for £38! |
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| Author: | pash [ 08 Oct 2012 21:00 ] |
| Post subject: | Re: Engine fault light |
I will have a look to see if I have one I can lend you to try. PM me your address. PS. Did you check for a short to ground? |
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| Author: | banjo1t [ 08 Oct 2012 22:48 ] |
| Post subject: | Re: Engine fault light |
Drat! I did not check for the possibility of a ground fault, will report back shortly..... |
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| Author: | banjo1t [ 09 Oct 2012 15:31 ] |
| Post subject: | Re: Engine fault light |
Right, I've double checked wiring, full loop and no sign of a ground leakage... |
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| Author: | GarrCano [ 09 Oct 2012 17:09 ] |
| Post subject: | Re: Engine fault light |
Maybe you can swap the signal wires on the ECM connector to perform the test which Kevmean told you. With a little luck the wires are close together on the same ECM connector. |
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| Author: | banjo1t [ 09 Oct 2012 19:14 ] |
| Post subject: | Re: Engine fault light |
Have considered this, however the time it would take to dismantle the harness, disconect the leads, reverse them, then having to put them all back again, and sods law, you can never get it back to it's original state, and knowing there was nothing wrong with the wiring in the first place!! |
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| Author: | kevmean [ 09 Oct 2012 19:35 ] |
| Post subject: | Re: Engine fault light |
swap the 02 sensors totally ie put the front one in the rear header and the rear in the front header ..... if the problem goes to the front then you know the fault is the sensor ............ if it keeps showing the rear then you know it's some other fault 
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| Author: | gunter [ 09 Oct 2012 19:37 ] |
| Post subject: | Re: Engine fault light |
It seems easier to me to go for a ride and log some runtime data, which will most probably show what seems to be the trouble ... |
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