P025a

[Lancefitzgiben]

Gents,

 

Toward the end of a 250 mile rip a few weeks back I was greeted with engine code P025a which seems to be tied to the fuel pump module. I had the light, but no symptoms.

 

Fast forward a week and the car began stalling when I entered a coasting condition - at least at lower (parking lot) speeds. The engine will restart and run fine, but stalls when you close the throttle or kick it into neutral for a moment. At this point I have the symptom, but not the light.

 

Any experience with something like this? I'm slowly learning all about this little guy, haven't messed with the fuel system yet though - I don't even know where the module is! On the Caterham Parts site it looks like a simple plug-in job with mounting tabs. Thanks for any insights.

 

2014 485S SV, 5k some-odd miles.

 

- Tim

[Croc]

Can I clarify please - where is the code showing?

 

The standard Caterham MBE ECU on a Duratec is not OBDII unless it was upgraded from standard so I would not normally expect a reader to see a code. The readers just do not read the ECU. Is it appearing on the dash electronic readout or are you getting it off plugging the ECU into the laptop and looking at it on Easimap app?

 

If you are getting it off an OBDII reader then I would be wary of the readout. On my ex-2004 zetec Cat with the Ford Oak ECU, I did get OBDII readout but I also had a bunch of faults around fuel tank, fuel pump, transmission, etc simply because the original Ford Focus ones had been replaced by Caterham pieces. You could be getting one of those false echo faults.

 

P025a can mean a bunch of faults depending on the car manufacturer:

- transmission - usually auto which obviously is not the case for you!

- fuel pump module as you point out

- 02 sensor failure

- catalytic converter

 

Can I also clarify one extra thing - you say it dies when you kick it into neutral. Is it because you came off the throttle or is it just because you selected neutral on the gearbox. I think you mean the former?

 

Sounds more like a throttle position sensor or something with the fuel/air mix at idle is my initial reaction.

[Lancefitzgiben]

Thanks Croc! Yes, I guess I could have given more information.

 

I'm using a standard issue cheap-o bluetooth OBD reader plugged into the port as installed in the car by Caterham - or whoever built that aspect of the car. The car came "new" to me and is stock, at least in terms of ECU etc. I've had some codes previously indicating a lean condition and limiting revs to 6k. I replaced my MAF (previous one had taken an oil bath due to my ignorance) and haven't really seen that one again.

 

I'm going to need to drive the car some more to figure out exactly what's going on when it happens but from what I recall - upon entering my neighborhood and dipping the clutch to select first gear (at 10mph or so) the engine died. When I went to take it out the other day, same thing happened albeit at the end of the driveway and at a much lower speed. I haven't had it cut out while driving down the road at speed, just these low speed occurrences. It does seem to start and idle just fine - but I will need to take it out and see if that changes when warm.

 

All this being said, let me know what to look at and I will report back - I've learned a lot about this thing in the last 4 years, but nothing that helps with this scenario - or anything having to do with electrics.

[Croc]

I have to admit I am puzzled you are getting OBDII read out. Maybe finding and telling us what ECU brand/model you have please? Usually somewhere near the battery or failing that in the passenger footwell. At least that will tell me if you can take the readout code seriously or not which may make the problem solve simpler.

 

I would do a test drive around your neighborhood to determine how/when the engine is cutting out - both in cold and warm engine states. Is it clutch related or throttle related? Can you dip the clutch and blip throttle and not have it cut out? Does it change when you down change gears versus up change? Are the brakes being used or not. Whats the maximum speed the cut out seems to stop happening at? Try a variety of things - the more view of the symptoms we have the better chance we have of seeing a pattern and determining likely causes.

[Lancefitzgiben]

I found this under the battery - looks like the ECU to me.

 

I drove the car around some and of course, didn't experience any issues. I will take it out on my normal Saturday rounds and see what happens..

 

- Tim

[Croc]

Yes that is your ECU and that ECU is not your usual one you find in a Caterham. It comes from a 2005-2009 era Lotus Elise or Exige. A previous owner has gone to a lot of work to make this switch - thats not your normal ECU replacement. It was the ECU on a 1.8L Toyota engine. Not familiar how easily modifiable these are for tuning but I guess it can be easily custom mapped? Other Elise/Exige owners on here can chime in.

 

Someone did something pretty special on this build. Are you the first owner? Did you need OBDII to pass NM emissions? I think this was an early Hillbank car from recollection?

 

The best Lotus specific error code list I could find is here:

https://www.lotustalk.com/threads/comprehensive-obdii-list-elise-exige.281258/

or here

http://gglotus.org/ggtech/elise-obd/elise-obd.htm

 

 

But that is only part of the error codes. You also have generic error codes which is what P025a is.

 

 

Still does not tell me if that error code is valid since we do not know if the previous owner wired the Caterham fuel pump control module it into the ECU? But in addition to trying to replicate the stalling problem by test driving it, there is also something you can check:

 

Lets assume the code is valid - I then suspect you have a loose wire to the fuel pump module which is intermittently stalling you. Thats more likely than the fuel pump module itself failing - although it is still possible. I would locate the fuel pump module - should be somewhere near the fuel pump. Assuming this is still standard Caterham then the fuel pump is a drop in type (fully immersed in tank) - so somewhere around the fuel tank. You will have to remove the boot floor to see it or come up from underneath. It looks like this:

https://caterhamparts.co.uk/pumps-senders/5336-fuel-pump-module-seven-485.html

 

Check the wiring from it forward into the loom for evidence of loose connection or fraying that would break the connection. Inspect the module for evidence of failure. You could take the chance and replace it if you want.

Edited November 14, 2020 by Croc

[Lancefitzgiben]

Thanks again Croc, you're a wealth of information!

 

To the best of my knowledge the car did come in through hillbank back in 2014 with ten or so other Caterhams. From there it was sent to the Florida dealer where it sat until they folded. Marshall Goldman bought their remaining inventory from auction and I got it from them. It had only been through the dealers and was never otherwise titled or registered. I think I got it with around 100 miles on it. I don't need emissions checks in my county, no.

 

I'll have to look into the info I have, at one point I did get some build info from Caterham about it. I'll also have a poke around today and see if I find that little module.

 

Thank you again for your help

 

- Tim

[rich]

It looks like a 2005 Elise ECU (2006 and up had a heat sink cover). However, the 2005 ECU had one large and one small plug rather than three small plugs for the electrical connections.

[Lancefitzgiben]

I made several trips in the car today and didn't experience any symptoms - ran like a top. I did however have the CEL come on again with the same code. It cleared fine and two more drive cycles didn't bring it back. I can't say under what circumstances the light appears - I can't keep an eagle eye on the cluster and it's difficult to see the light anyway.

 

A quick poke around underneath the rear revealed the module on the left side of the vehicle, but all connections seem snug and wires in good shape. I only visualed what I could see from crawling around underneath.

[Croc]

Chasing intermittent electrical glitches can be frustrating. If it is not stopping you from driving then you just keep monitoring I suppose.

[Lancefitzgiben]

Yep, for now it's just one of those things. It's not like the lean code I've had that taps me out at 6k rpm. Since performance isn't impacted I'm not especially bothered, but it's nice to learn more about the little thing!