EP3 Lambda sensor wires were cut - twisted together

[xsimonb]

Just wondering what damage could have possibly happened. My EML light was on - Fault was the Lambda sensor

Turns out that some muppet had cut the 4 wires from the plug to the sensor - twisted them together and wrapped tape around them all. Is that not feeding 12V back into the ECU?

Replaced with a new sensor and now getting an error code for high voltage

Is their anyway to check my ECU hasn't had loads of damage to it - its a K100 ecu in the car.

Thanks

 

[Hazz]

Voltage won't be an issue, the question is what effect has it had on your AFRs?

 

[xsimonb]

Whats an AFRs haha

Was thinking that voltage wouldn't be an issue - if it has an earth wire that was twisted (and is properly connected) the voltage would just shoot straight to earth... although I would have thought it would have melted the wire aswell

 

[Chris.]

Voltage doesn't go anywhere, it drives the current. Think of voltage as water pressure and current as the water itself.

Did the loom get replaced as well as the sensor? I can't remember if they are part of the same thing or not. Did you get an ECU reset after fitting the new sensor?

 

[xsimonb]

They replaced the sensor and loom can't remember if they said they tried resetting the light - I imagine they would have but unsure. So basically the ECU shouldn't have had any voltage in it as it would have went straight to the earth right?

Oh wait they did reset the light and now it says voltage is too high...

 

[Chris.]

Are the fault codes exactly the same from before and after?

 

[xsimonb]

Previous fault code was to do with heater circuit

this one says voltage is too high

 

[Chris.]

What brand sensor? Was it a Honda one or 'cheap internet' one? Faulty sensors can cause both codes but it is not always the sensor. I'd get a decent garage to diagnose.

 

[Hazz]

Try an ECU reset, it might just need to learn the new voltages.

I forget the fuse number you need to pull, I have 13 in my head but let me check...

Edit: as chris said, make sure it's an OEM quality sensor.

 

[Chris.]

I think it's 6.

 

[Loxy]

I think it's 6.

Yup, the box in the engine bay.

 

[CTR_Nick]

AFRs = Air-to-fuel ratios

The ECU has a table of values based on throttle input and engine speed that say how much fuel to put in at any given point. Having a bodged Lambda input to the ECU could have played havoc with the AFRs because the ECU constantly adjusts the amount of fuel going in based on what the lambda sensor sees in the exhaust flow.

However, if the wires were all connected the sensor I believe you are correct and it would have grounded. I don't know whether the Honda ECU would have then ignored that or just read it as being very, very lean (lambda sensors output between 0 and 1v).

If it's now reading high voltage, that would suggest to me that there is either a short or a wrong connection somewhere and that could be the reason it was bodged, to clear that fault.

 

[Lewisgame]

I'll assume this is for the primary lambda sensor?
I'd check it's been wired up correctly. As there is 2 circuits (4 wires) for the lambda on this vehicle. 2 are for the heater circuit (at 12v) the other 2 for the oxygen sensor side (0-1v). If you mix these up, you'll get some funny readings and fault codes.
Example could be heater 12v supply connected to the signal for oxygen level. ECU seeing 12v where the signal should only be between 0-1v. Fault code being high voltage... obviously.
Also as mentioned, a good quality sensor must be used. Either genuine Honda or an NTK brand sensor.


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