Mitsubishi Shogun 3.0 petrol P0125 stored

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Mitsubishi Shogun 3.0 petrol P0125 stored

Postby Darren Cotton » Sat Jun 18, 2011 6:40 pm

I was asked to look at this Mitsubishi Shogun with EML on. This had already been looked at by another garage, the customer has taken it back to them twice with the same problem and they have failed to fix it despite money already spent.

These jobs as we all know can be a problem, the customers budget already spent on unnecessary parts and time by the previous garage, and the pressure is on to get the diagnosis right first time.

A challenge I like and I agreed to take the job on. After interrogating the customer I started the process, first thing code read.
Fault codes Shogun.gif
Fault Codes

P0125 - Insufficient coolant temperature for closed loop fuel control

A code I have never seen before. Done a visual check and could see a thermostat and an engine coolant temp sensor had been fitted by previous garage

I decided to monitor live data from cold to running temperature, not 100% sure what i was expecting but just looking for anything out of the ordinary.
Shogun data..gif
Live Data

Live data showed engine coolant and air temp as normal, but scrolling down the data I noticed Bank 2 sensor 1 only reached a maximum of 0.24v during the whole warm up period which was about 30 Mins
This was the only thing that stood out to me,it obviously was not right, now I needed to find out what was happening and could this be related to my fault code.
The connection block for both O2 sensors was fairly accessible at the bulk head, resistance across the heater circuit was 7 Ohms, once engine had cooled down again I connected the scope and used all four channels. Measuring signal, supply, duty cylce for heater and heater current, earthed the scope at the sensor

Every thing except the signal was normal, as serial data showed, bank 2 sensor 1 was around 0.2v.
I wanted to see what the sensor would do with a snapped throttle, so I freed up the channels and I introduced bank 1 sensor 1 with bank 2 sensor 1 and throttle position, snapping the throttle we would expect to see a rich state through out the WOT (Wide open Throttle)


Uploaded with

As pointed out the green trace is bank 2 sensor 1 on wide open throttle the sensor goes sub zero, something that I have only seen a few times.

This would have never been discovered with out the pico, Maybe this is why the other garage struggled.......

Don't get me wrong here this was a complete learning curve for me as I have never experienced the fault code before, and didn't really have a diagnostic structure in place. It was a kind of earn as you learn repair, either way, new O2 sensor was fitted and then carried out another WOT test with both sensors, and proved both sensors at a rich state during the WOT and no sub zero voltages.

Fault code cleared and extended road test performed, connected scan tool, no fault codes present or pending.

The pico was infallible in this case, it just shows a bit of time and the right tools you get a fix and no unnecessary parts fitted...

Darren Cotton
Last edited by Darren Cotton on Sat Jun 18, 2011 9:37 pm, edited 1 time in total.
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Re: Mitsubishi Shogun 3.0 petrol P0125 stored

Postby Robski » Sat Jun 18, 2011 8:02 pm

Very nice Darren :wink:
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Re: Mitsubishi Shogun 3.0 petrol P0125 stored

Postby Lee » Sun Jun 19, 2011 9:58 am

Hi Darren

This is a great case study!

Showing how both faults codes can be slightly mis-leading in some cases and how the Scope was able to show key information.

Good Work and a good read.

Kind Regards

Lee - Automotive Technical Specialist :D
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Re: Mitsubishi Shogun 3.0 petrol P0125 stored

Postby Apprentice » Wed Aug 31, 2011 1:10 am

Good case study Darren

What diagnostic equipment did you use for this?

I ask as the generic EOBD fault code description you mentioned is probably not the correct one for this vehicle, I believe the correct interpretation for this error code on this and many other Mitsubishi models is as below.

P0125 :- Excessive Time to Enter Closed Loop Fuel Control

So well done for finding the problem despite having a misleading description of the actual fault.
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Re: Mitsubishi Shogun 3.0 petrol P0125 stored

Postby Damian Mc Bride » Sat Sep 03, 2011 8:56 am

Good job Darren :D
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