Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 M3W EML/CEL P0173 – What are my options?

My 2019 Three Wheeler has had an intermittent EML since I bought it, “P0173 Rear Adaptive Maxed Out.”
The car drives fine, and from what I understand, it is one of many common fault codes that these cars can lovingly throw at you.
Sometimes it disappears for a few dozen miles, other times it stays on for months.

Every year, the technician at Morgan resets and clears the code for me, but it always comes back no matter what.
He has always said not to worry about it, it is common, and to just ignore it – apart from a reset, there isn’t much they can do about it.

Whilst physically seeing the light is annoying, for 3 years now I have put up with it and enjoyed the car thoroughly.

The problem is, I’m starting to get to the point where I feel I want to sell the car and experience something new but selling a car with a check engine light and saying to a possible buyer “oh I promise the car is fine” won’t go down well, and will make the car almost impossible to sell unless I take a bath on the price. I doubt I could PX it, either, at least not for a reasonable valuation.

Obviously, I could have the fault cleared and try to avoid using the car until it’s sold in the hope it doesn’t reappear until it’s the new owners problem (which I suspect is what the previous owner did with me) but I’m not a dishonest seller and don’t feel comfortable doing that.

So, what are my options?
Is there a way I can log into the ECU and clear this code myself? I have got a copy of Pro Tune but it doesn’t really seem to give me any control.
Can I get the sensor that causes this EML “turned off” or increase the thresholds that cause it to go off, to prevent it from happening again?
There must be something that can be done – surely the car can’t be stuck with this forever?

With Protune you can connect to the ECU and read and clear the fault code.

P0173 is a result of the air/fuel mixture going out of the prescribed limit. The ECU has a baseline setting map and an adaptive range which allow the ECU to trim the mixture in real time based on the revs and input from the lambda sensors. Your car is requiring too much adaption hence the light.

The most likely cause is a dirty of failed lambda sensor so changing one or both of these might help. They are listed in the Alternative parts list.

Before changing do a though check that there are not leaks in the exhaust upstream of the sensors nor in the intake pipe from the throttle body to the inlet port. Check the throttle body gasket and that this is firmly bolted in. Even a slight leak could trigger the light.

Thank you, Chris.

Something I didn't mention, which may have relevance - my exhaust isn't standard. I believe it to have been fitted by Krazy Horse at some point prior to my ownership (I have tried to contact them for clarification but they never respond or call back) but the air filter and ECU are all standard as far as I am aware. Could that have anything to do with it?

Appreciate the advise, it gives me somewhere to start.

As noted by Red Leader, the ECU makes dynamic adjustments to the air/fuel mixture. If your car has a low restriction exhaust system fitted, it will likely throw the P0173 code on an unfortunately regular basis. The ultimate fix (assuming no other issues-follow RL's advice on checking for these) is to procure an unlocked ECU which allows you to capture the adjusted operating parameters and store them as a new baseline map, from which the ECU can again make dynamic adjustments.

Just as a reminder, the dynamic adjustments the ECU (standard or unlocked) makes are lost if the battery is disconnected for any reason. Hence the value of the unlocked ECU with which you can record the adjusted map file using the ProTune software.

With the same problem ( , not original exaust , ) on an 4 wheeler , we placed an adapter between the exaust and the lamda sensor ( 9 € ) and the light stays out .. MOT , no problem anymore. You can find these adapters at exaust tuners ( internet ) Worth a try

Stefan

+4
+8
ARP4
PlusFour

True the adaptive settings are reset back to baseline if you power off the ecu for more than a few seconds, however it will quickly retune the adaptive settings next time you start the car. My car is garaged with the battery disconnected, sometimes for weeks at a time and I've never had an engine light issue.

With an unlocked ecu you can, if you like, merge the adaptive settings into the base map so it then uses a preadapted map as the baseline. For info my car is garaged with the battery disconnected, sometimes for weeks at a time and I've never had an engine light issue.

Depending on how open the aftermarket exhaust is it can require nearly all of the standard adaptation and if it goes out of range, even momentarily, it will trigger the engine light. This is then locked on for around 10 or so engine off/on cycles and if it doesn't go out of range again it will go out on it's own.

Krazy Horse have fitted a number of different exhausts over the years and most are fully OK with the standard ecu. I believe there can be an issued with the Demand Engineering "Demon" exhausts but can't be certain.

If you could find it an unlocked S&S ECU would be £500-£1,000 and the proven alternative Emerald ECU is £1,000 plus. However even on the stock ecu the engine should run OK with a suitable Stage 1 exhaust and functioning Lambda sensors.

For replacement Lambda sensors contact andy.warren@yahoo.co.uk as he can supply improved replacements cheaper than MMC. He may well have some ideas on how you can test the existing ones.

The other approach would be to swap the exhausts for stock. I have a virtually unused pair of stock exhaust pipes which you're welcome to foc if you can collect them from Sussex. Alternatively I am occasionally in Essex (nr Stansted) so you could collect them from there if the dates work.

As a last point - the check engine light is an MOT fail so it definitely would cause problems if/when you sell the car.

If it is "out of adaptation" range you and its only one one cylinder you could try swapping the injectors over (its port injected so easy to swap). The injectors are controlled by pulse width, so if they are partially blocked they will require a longer pulse to achieve Stoich which might be close to the edge of the map. The VE map is locked. Failing that try the exhaust Wideband lanbda sensors incase it's trying to correct a fuel t air ratio that isn't really out. Both are readily available and ProTune is easy to hook up. Good luck!

As Chris99 says, it could be the Lambda sensors? Try transposing them and see if the snag switches from PO173 (rear cylinder) to PO170 (front cylinder). If the PO173 remains it's not a Lambda sensor at fault. Codes PO170 and PO173 are often caused by a fuel supply pressure issue with the ECU extending the pulse to make up for a low delivery pressure. Do you have the original fuel pump fitted or has it been replaced with a more reliable Walbro one? The original fuel pump is the cause of many running problems and should be replaced. You would think that a faulty pump would give problems with both cylinders but it usually just indicates one cylinder, the fuel maps are not identical front and rear.

The standard locked ECU will normally manage to operate with a free flowing exhaust without fault codes, I doubt that is the problem but you could ask your dealer to install a Stage 1 map if you have concerns. Not sure how much they charge for that these days??? Worth sorting it out if you are planning to sell as a frequent EML will not help a sale. The fuel pump parts are not expensive, a bit over £100.

Thank you, Chris.
I think taking you up on the offer of free pipes would be very appreciated. I'm Essex, so not too far from you - I'd just need the dates to work (ideally from the Stansted). Are they one long piece or do they break down? I may need to borrow a car to put them in, my daily is a little MX5!

Usually, Len at Brands Hatch Morgan resets the code so it clears when the car goes in for its MOT and service, which is why MOTs haven't been an issue in the past. He has generally stated that there is nothing they can do to fully resolve it and always provides the reasoning that different driving styles are why it flags up; however, all the comments in the forums from others who have experienced it clearly suggest otherwise. It's frustrating as understandably, nobody is going to buy the car with the EML on, even though it runs fine. I don't really want to sell, but 3 years in over 2x 3 Wheelers, the itch is scratched, which is why I am contemplating it.

Yes I will try swapping the sensors when I get a chance, they appear to be easily accessible so I presume it's easy to do this - it'll be interesting to see what the outcome is.

I don't know if I have the original fuel pump but I would assume that I do. I bought the car at 3 years old and 2,000 miles and whilst the exhaust was modified (I assume), I don't seem to have a receipt for a fuel pump. Where can I buy a Walbro fuel pump and are there any additional parts I need? Is it an easy install and is it "plug and play" or does any coding need to be done wit the MOT?