Strange o2 Sensor Fault

[GhostRiderZZ]

Hello All,

I was wondering if anyone had any ideas regarding the following:

Since purchase, my bike has had an intermittent fault with the engine management light coming on after a short ride, with a P0130 fault showing (O2 sensor malfunction)

When connecting up Dealer-Tool - the o2 sensor voltage is permanently showing 4.98 volts, it does not change whether I unplug the o2 sensor from the harness.

I have attempted to put one of the delete plugs in, which have a couple of small resistors to fool the ecu...however the voltage still shows a solid 4.98 volts and throws the check light.

Short of tracing back the entire wiring harness to look for issues, does anyone know of any reasons this may be showing up - is there another connection on the harness that I need to look at??

Cheers 

[Coconut]

For What It's Worth, my O2 Sensor shows the exact same voltage
when connected to DealerTool without the engine running.

I haven't checked it with the engine running and won't have time to do so for the next few days.

Why did you try fitting a "Delete Plug" - If it was to try and test whether the O2 ( Lambda ) sensor
was working, in respect of the intermittent Fault Code, that probably isn't the best way to go about it.

I cannot and will not provide any guidance or information on permanent removal of the O2 ( Lambda ) Sensor,
as ( in the UK ) doing so and then using the bike on a road, would possibly result in an offence being committed
and the discussion of such matters would probably not be permitted on the Forum.

To try and help find out what is wrong though .....

As you purchased DealerTool, you could reach out to their Support Team, ( support@dealertool.co.uk )
and ask what readings you should expect to see on DealerTool for the O2 Sensor,
i.e. Is it just confirmation of the 5 Volt Sensor supply, or should the indicated voltage change
( and to what values ) in different engine operating climates.

Meanwhile, the DTC Code quoted "P0130" - Oxygen sensor circuit malfunction,
is dealt with on Page 10.72 of the Service Manual,
and gives the following Pinpoint Tests for the 4-wire O2 ( Lambda ) Sensor:

Ensure the O2 ( Lambda ) Sensor is secure, and disconnect the ECM.

Test 1
Check cable and terminal integrity at ECM Pin A21.
If OK proceed to Test 2, If faulty, rectify and proceed to Test 4

Test 2
Check cable for short circuit - ECM Pin A21 to Ground.
If OK proceed to Test 3, If Short Circuit, locate and rectify wiring fault then proceed to Test 4

Test 3
Check cable continuity :
ECM Pin A21 to O2 ( Lambda ) Sensor Pin 2, and
Ground to O2 ( Lambda ) Sensor Pin 1
If OK - Renew O2 ( Lambda ) Sensor and proceed to Test 4,
If Open Circuit - locate and rectify wiring fault then proceed to Test 4

Test 4
Reconnect Harness, Clear Fault Code, Run engine and check Adaptation Status.

Circuit Diagram :



Let us know how you get on, including any response from DealerTool
as this may help another Trophy Owner in future with the same problem.

Cheers 





 

[STJIM]

It sounds like you have an open circuit in the wiring somewhere or an open circuit inside the the O2 sensor itself.  O2 sensors usually don't fail this way, they usually wear-out after high mileage.  But you never know what may happen.

If you are able, try unplugging and re-plugging the connectors in that circuit.  Before re-connecting, inspect to make sure the male pins are all protruding equally into the inside of the connector.

If that doesn't clear the problem, try measuring the resistance across the wires of each connector in the O2 sensor circuit by back-probing with safety pins inserted into the back of each side of the connector.

And BTW, an O2 sensor is really a gas sensor.  For a very lean mixture it's output is close to zero volts.  For a very rich mixture it's output is close to one volt.  So it's output depends on a high ratio of gas to oxygen, , not the ratio of oxygen to gas.  It's actually "detecting" gas, not oxygen.

[GhostRiderZZ]

Thanks for the comprehensive replies peeps, most appreciated!

To answer the initial question, my fear was the o2 sensor was completley knackered (would not be surprising as the bike has over 50k miles on the clock), as you dont usually see voltage ranges over 0.9v during operation on any o2 sensors I have come across in the past. An easy quick test was to first unplug the sensor and then use a plug delete to check for any changes, unfortunately they resulted in no difference and the same sensor fault continued as before.

As is usual with fault diagnosis, its often good to try the easiest options first....and as I do not have access to the service manual for the bike, I did not have the information regarding the specific ecu pin out and what to look for as mentioned by Coconut above.

As the wiring disappears into the main wiring loom its difficult to follow or know exactly where it goes.

The above suggestions are most appreciated, as soon as I get chance I will take a look and report back what I find.

Cheers!

[Coconut]

I had chance this morning to check the O2 Sensor readings on my Trophy with the engine running.

As noted previously, WITHOUT the engine running, the Voltage for the O2 Sensor shows 4.98 Volts.

After starting the engine the Voltage Reading did not change at all - initially -
until I switched away from Page 4 to another of the Sensor Values Pages,
then went back to Page 4 - which now showed the updated ( and constantly updating ) readings as below.
 


I'd suggest double checking this, and try clicking off Page 4 then back onto it
after starting the engine, which seems to "refesh" the details on the page. 

Cheers 

[STJIM]

So I wonder what the #1  and  #2  is all about ??   The only thing I can think of is numbered successive readings ?

So BTW,  after an O2 sensor is warmed up ( there is a heater inside the O2 sensor to speed up the time to closed-loop operation - between pins 3 & 4 in Coconut's diagram above  ) the sensor voltage should alternate between a low reading and a high reading fairly quickly.  Usually this check is done above idle RPM, in a  car above 1,500 RPM.  The voltage should switch fairly often once in closed-loop, like every second or so. 

This is true only for a narrow band sensor which I'm willing to bet is used on the Trophy.   Some newer cars use a wide band sensor which is a different animal altogether.   A wide band sensor voltage doesn't alternate quickly between a low and high voltage like a narrow band sensor.

[Coconut]

Bear in mind that the DealerTool software is not exclusive
to the Trophy, and covers many Triumph Models.

Perhaps there is a Model with dual O2 Sensors,
or it caters for differing types of O2 Sensor on different Models ?

Cheers 

[GhostRiderZZ]

Unfortunately the voltage reading on mine sticks at a constant 4.85v even clicking away from the page and back when running for some time.

I am guessing there must be an open circuit somewhere, so its going to be taking the bodywork off again and continuity testing from the ecm pinout (as image provided by coconut above details) and the o2 sensor connector to check for any open or short circuits.

I will post what I find