K Series ECU / MIL Light

[JosephClarke]

Hi All

I already owned an ODBII reader so decided to hook the caterham up just to see what was logged etc.

The ECU had 4 codes logged but unfortunately it does not record distance traveled since they were logged to no idea how long they have been there.

Couple of questions, the ECU thinks the MIL (engine warning) light is illuminated however nothing is illuminated on the dash, the car is a 2002 k series with the classic (dial based) dash. Does the car actually have an ECU light to illuminate?

Second question, due to the ECU and loom being rover based, are there any common errors that are always logged due to parts missing from the Caterham that would have been in place in a Rover?

Thanks all.

[SM25T]

The Mother in Law warning light !! :-)

[revilla]

Yes there are a few DTC codes that are commonly logged due to compoments of the Rover system being omitted on a Caterham. For this reason there is no MIL light as it would be almost permanently on. Anything relating to Evaporative Emissions / Charcoal Canister or Post Cat Lambda Sensor / Bank 1 Sensor 2 can be ignored. There are a few other common ones too. Post up the codes you've got and I or somebody else will be able to tell you if there's anything there to worry about.

[JosephClarke]

Thanks very much, I have cleared the codes so will take the car for a few runs then post up what is logged.

cheers for help

[JosephClarke]

Ok after a good run today I have the following logged

P1590

P0195

P0135

P0141

Thanks

 

[revilla]

P1590 - Rover Specific - Fault in ABS System - You haven't got one, ignore it. I've seen this often enough before, I think the ECU is just confused because it isn't getting communications with the ABS module. I think this code is a general one that tells you to scan the ABS module for faults as well as the main ECU. Don't worry about it.

P0195 - Generic - Engine Oil Temperature Sensor Malfunction - You haven't got one (only VVC engines do), ignore it.

P0135 - Generic - O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1) - That does suggest a problem with your lambda sensor heater circuit. Bank 1 Sensor 1 is the one lambda sensor you DO have.

P0141 - Generic - O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2) - You haven't got a Sensor 2 (Post Catalyst), ignore it.

So the only thing to worry about is whether your lambda sensor heater has burned out or whether there's a fault with the wiring to it. I have seen one obscure case where this was caused by the driver circuit in the ECU being burned out, but the first thing to do is make sure the plug is secure, the wires don't look damaged, then possibly try swapping the lambda sensor. Given that you don't have any other lambda sensor related issues reported, it's possibly not the end of the world, the sensor will heat up in the exhaust gas anyway but the heater is there to get it up to its 300C operating temperature as quickly as possible.

[JosephClarke]

Thanks for that, really useful.

Will check the wiring etc as suggested and go from there, the car does seem to have trouble driving from cold it likes to be left 30 to 60 seconds to warm up else it seems to bog down when trying to pull away.

 

[JosephClarke]

Hi, after clearing the codes and checking the wiring this is still coming back,

P0135 - Generic - O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1) - That does suggest a problem with your lambda sensor heater circuit. Bank 1 Sensor 1 is the one lambda sensor you DO have. - See more at: http://www.lotus7.club/forum/techtalk/k-series-ecu-mil-light#sthash.9Y84ZBuI.dpuf
 

Could anyone recommend a good supplier of the correct Rover (OEM) Lambda sensor that Caterham use?

Thanks

Joe

[Jonathan Kay]

Do you know which type you want?

Jonathan

[Peter G]

Try Rimmer Brothers. But as Jonathan says you do need to know which one you need.

[JosephClarke]

The car is a 2002 1.4 K series, I am not hugely up to speed yet on K series versions, is EU3 a generation version of the K series? I have read a lot about distributor caps etc on K series but mine looks to use coil packs so am assuming it's a late K series?

This looks identical to mine but will check the part numbers on the one on the car. Thanks

http://caterhamparts.co.uk/product.php?id_product=1056

[Jonathan Kay]

"EU3" is a type of ECU. But I don't know which sensors or ECUs factory 1400s came with when.

Jonathan

[Roadsport06]

EU1 onwards is the emissions standards that a car needs to meet. K series went from eu2 to eu3 around 2000. EU3 is wasted spark, no distributor. Yours will be eu3, that was as far as k series went. The latest emissions standards for cars is eu6

[Roadsport06]

This explains eu1-6

https://www.theaa.com/motoring_advice/fuels-and-environment/euro-emissions-standards.html

[JosephClarke]

Lovely, thanks will have a read.

[p.mole1]

You can test a Lambda sensor by removing it, these things are expensive.

There are four wires two go to the heating coil you can check those easily enough,the other two sensor wires provide a voltage when heated,about 0.2 to 0.9 V. All you need is a multimeter and a blow lamp,

DO NOT TEST FOR RESISTANCE THOUGH THE SENSOR WIRES this can damage the Zirconia sensor these are very delicate.

Have look on Youtube loads of videos showing you how its done

[JosephClarke]

Sadly suffered my second brake down in as many weeks, have managed one trip out in a month without breaking down!

This time the car seems to be having real issues idling until hot, the car constantly kept stalling while driving through city center traffic, it seemed as though it couldn't maintain an idle as soon as I let of the throttle to brake or change gear it would cut out.

I haven't checked the lambda sensor yet but it is still flagging the P0135 code even after resetting the ECU.

However it is also now logging P0501 which seems to be related to an engine speed sensor.

I am going to test the lambda sensor and wiring tonight, what I am wondering is if this is likely to all be related to the lambda sensor (it seemed to idle once up to temperature) or if this new code is the cause of the stalls.

Does anyone know much about this code, searching the forum came up with one post detailing a process to cause the ECU to relearn the throttle position sensor values so I am going to try that as well.

Fun fun! I really just want to get out for a few drives and make it home again :D

[Ian Mackenzie]

If the wiring checks out OK you should be able to get a new sensor for circa £50 from a motor factor or good old ebay: 

http://www.ebay.co.uk/itm/Genuine-MG-Rover-BOSCH-Oxygen-Lambda-Sensor-200-400-25-45-MGF-TF-ZR-ZS-MHK100840-/371492900204?fits=Car+Make%3ARover&hash=item567eb3cd6c:g:f-EAAOxyVLNS8m-D

​Strange P0501 is now logged if it was not before? Seems to refer to the vehicle speed sensor.....which I don't think the Caterham uses.

Regarding the idle.....the Idle Air Control Valve controls the idle speed, but an incorrect fuel/air ratio can also stall the engine or lead to rough idle, but I'd focus on getting the Oxygen sensor fixed first as this clearly wont be helping things and could be the solution to all the symtoms...

Cheers

Ian

[simon_h]

Joseph,

As you know P0135 is lambda sensor bank 1 sensor 1 heater malfunction, this is the generic description for the code. Most likely to be an issue with the wiring but if I remember rightly the EU3 Rovers (1.8l did) drive this direct from the ECU so in the worst case that could fail.

P0501 should be vehicle speed sensor range/performance. Again this is the generic description but I expect Rover kept it. I dont think the Caterham application has the wheel speed input into the ECU so this one will never go.

I am just up the road from you and I think I have a O2 sensor in the garage you could try. PM me if you want to pop over one evening / weekend.

Simon

[JosephClarke]

Thanks all, will do some investigation tonight.

Simon PM sent.

[revilla]

Simon is absolutely right, the ECU drives the heater directly and I've seen one where the drivers in the ECU had failed which did indeed give the same code you are seeing. If swapping sensors doesn't cure the error code, you can check the ECU drivers by connecting a 21W indicator bulb across the two pins on the wiring loom connector that drive the heater. This presents a similar load to the heater circuit. Unplug the lambda sensor first and wire the bulb across the two pins that correspond to the white wires on the sensor. When you first start the engine, on a healthy car the light flashes at full brightness maybe twice a second as the ECU pulse-width modulates the power to the heater. On my friend's car it just lit up to a continuous dull glow. Swapping the ECU fixed it.

Be very careful testing the sensor itself with a multimeter, if you stick in ohms mode across the sensor itself by accident it will damage it.

However ... I don't think that the failure of the lambda heater circuit would give your idle symptoms. The heater is only there to get the sensor up to temperature quickly and it soon heats up in the exhaust gases anyway. When it's not up to temperature the engine generally ignores it and runs off the default base map in open loop mode and the car wouldn't normally have serious issues with idling.

It is possible that there's more wrong with the lambda sensor than the heater. If the heater has failed it might have built up soot deposits or something that could be stopping it reading correctly. As a quick check of whether that is the problem, you can just unplug it (which forces the engine back to the default map settings) and see if it is any happier. I'm not suggesting that you drive around with it disconnected for the longer term but as a quick check it won't do any harm. Power / emissions / economy etc. may be down a bit but it should basically run OK.

It does sound more likely to be something to do with the IACV or TPS or sensor readings to me. If the ECU's calibration of the TPS voltage is incorrect you can get idle issues. Switch the ignition on without starting the engine, smoothly open the throttle fully then close it again, five times. Then switch the ignition off. Then fire it up and see if it is any better.

Does you OBDII scanner have a "live data" facility showing values from the some of the engine sensors? If so, worth having a good look to see if the values it reports are sensible. You will see from this if the TPS is calibrated correctly, it should show 3.92% throttle at idle. Look at the intake air temperature and coolant temperature to see if they are sensible. Obviously you can't check them to the degree but they don't need to be that accurate, just make sure that the engine is getting something like sensible information. I had a wiring problem to my IAT sensor and it showed the intake air to be -40C which clearly wasn't right. If it thinks the coolant is hot when it is still cold, that would stop it enriching the mixture as it normally would.

The live data screen should also give you a bit of information about the lambda sensor. It should tell you whether it is running "Open Loop" (ignoring the lambda sensor maybe because it is getting implausible readings or because it doesn't believe the sensor is up to temperature) or "Closed Loop" (using the lambda sensor to trim the fuelling). Expect it to run open loop when you first start up then switch to closed loop when the sensor gets up to temperature and starts working, only takes a matter of seconds on mine. It will probably also show the lambda sensor voltage. Be careful as it may show you more than one, you want Bank 1 Sensor 1. Bank 2 would normally only exist on V engines and Sensor 2 is after the catalyst, which you don't have. If the lambda sensor is working normally, this voltage will normally be swinging up and down between around 0V and 1V (typically 0.1V or less and 0.9V or more), probably once a second or more. The ECU doesn't get enough information from a narrow band lambda to know how rich or lean it is, just that it is rich or lean. So it runs it a little richer until the sensor switches to "rich" then leans it a bit until the sensor switches to "lean", keeping it roughly right and bracketing the ideal mixture. The ODBII scanner doesn't get a reading frequently enough to follow this waveform and you see samples but you should see some readings towards the bottom end of the range, some towards the top and some in the middle if it is working; if you just see about 0.45V constantly that's a good sign that there is a wiring fault and the sensor is disconnected, the ECU input is usually biased to give approximately the "ideal" voltage reading when floating.

The other thing you can check on the live data screen is the MAP (manifold absolute pressure) sensor. With the engine switched off it should read around 100kPa (atmospheric pressure). With the engine idling you should get a good level of manifold vaccuum so it should be a lot lower, I can't remember what mine reads but I guess around 30kPa or even lower, and should rise as you rev it. Anything too far away from those numbers and you could have a problem with the sensor.

[CharlesElliott]

Is there a recommended piece of OBD2 software (for a PC)?

[JosephClarke]

Wow thanks what a ueful post, I have tested the sensor and it shows no resistance across the heater wires, I am going to follow through all the other points you made in the morning and then go from there.

It is looking like the lambda is shot at least the heater part so I think replacing will be a good start, hopefully a local member is going to let me test one of there spare ones.

I am using "TouchScan" ODB software, I think it covers off live data so will give all the above a try as well.
 

[revilla]

When you say "no resistance" I'm guessing you mean infinite resistance, as in the multimeter shows no response when you connect it to the heater wires?

[JosephClarke]

Yes as if it were an open circuit.