So, while I was changing out the brakes today (discs and pads all round), I came stuck when I realised that the calliper carriers were hooped. So while waiting on the order coming through for new ones, I gave the car a wee scan with a cheap, generic reader.

Anyway, this is the results... (See attached).

Now, I cleared the codes, and will run it a few days and re-check, as I have replaced the MAF already, so there may well be other lingering codes there too.

But, I couldn't find much info on the last two codes, P1590 and P1669. Any ideas?

And what would the EVAP be? I guess another sensor for that?

A system to prevent evaporated fuel (if fuel in tank gets hot and vapourises) from being released to atmosphere. Pretty complex system read up on in RAVE.

wammers said:

A system to prevent evaporated fuel (if fuel in tank gets hot and vapourises) from being released to atmosphere. Pretty complex system read up on in RAVE.

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......And I am not sure if it was only fitted to the NAS vehicles and as such not applicable to UK spec.

Saint.V8 said:

......And I am not sure if it was only fitted to the NAS vehicles and as such not applicable to UK spec.

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Indeed NAS only from 1998. Someone should tell the BECM it's not fitted. But it does show the value of cheap OBDII readers when applied to the Range rover. Pre cat Lamdas may not exist on UK motors either.

wammers said:

Indeed NAS only from 1998. Someone should tell the BECM it's not fitted. But it does show the value of cheap OBDII readers when applied to the Range rover. Pre cat Lamdas don't exist on UK motors either.

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I thought it was after cat sensors that did not exist on uk motors? I certainly have 2 lambdas ahead of the cats on mine. also I thought my thor has evap system fitted?whats that valve that's just behind the throttle body?

sassanach said:

I thought it was after cat sensors that did not exist on uk motors? I certainly have 2 lambdas ahead of the cats on mine. also I thought my thor has evap system fitted?whats that valve that's just behind the throttle body?

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Don't know not really interested in the gas guzzlers. Maybe i should have said post cat Lamda. If he puts some proper diag on it he may get more info. One of the systems fitted to NAS vehicles was to give OBDII readability. Can't be bothered delving into it.

From my reading, it looks like it was fitted to non-NAS vehicles too, but with a slightly different configuration.

For example, the Fuel Pump & Guage Sender Unit, incorporating fuel tank pressure sensor is NAS only, as is the CVS (Canister Vent Solenoid). Looks like most everything else may well still be present in ROW vehicles. Of course, the Workshop Manual I'm looking at could well be wrong.

The advanced evaporative loss control system used
on NAS vehicles is similar to the standard system, but
also includes a CVS unit and an in-tank pressure
sensor to monitor the pressure build-up for
determining whether leaks are present.

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Anyway, I will have to look into it further to see where the Purge Control Valve may or may not be. Further looking will be required.

As for the Lamda's, there were two fitted a couple years ago, according to my receipts, but they may well have been cheap and nasty ones. So they could well still be gone, or it may be that the codes weren't cleared and they are residual codes left over. Either way, I will re-scan the motor after a few days running.

As for the "cheap diagnostics", well, I have access to what I have access to. I can take it to my local specialist, and pay the £35 + VAT for a proper diagnosis, and I may still do that, depending on what comes up after a few days, just for confirmation before forking out on possibly unnecessary parts. But I am not up for spending hundreds of quids for a system to use on a motor I only plan to keep for 12 months.

UK spec petrols all have pre-cat O2 sensors - but NAS (and some other) markets were fitted with post-cat O2's which apparently are there to measure how efficient the cats are running at and will flag a fault if the cats aren't working properly (apparently)

EVAPS is on all petrol models too - the bit that NAS got was SAI - Secondary Air Injection - which is also something to do with emissions. UK spec and pretty much everywhere else in the world didn't get SAI.

EVAPS does work (from what I understand) on storing fuel vapour in the charcoal canister and then the purge valve releases this into the inlet manifold in bursts. Charcoal canister on the GEMS is up by the bulkhead behind the EAS box (where the Thor has it's ECU) and on the Thor, it's under the vehicle by the fuel tank (behind the transfer case)

The purge valves can fail - and I seem to remember seeing somewhere on rangerovers.net that there is a part listed for Hyundai which is compatible with the RR one but a lot cheaper!

I'll see if I can dig out the link, as the purge valve is really the only moving part in the EVAPS system and looks like the cause of the EVAPS code.

According to RAVE the other codes are:
P1590 - comes back as an ABS Rough Road Circuit Malfunction and description of "Hardware is OK, but SLABS ECU is sending an error signal"
P1669 - says that it is a Engine Control Module Cooling Fan Circuit Malfunction. Which if you have a Bosch P38, then the cooling fan is inside the box where the ECU is housed - If you have GEMS, then no idea as the GEMS doesn't have a cooling fan.

EDIT - Just seen your other post re the O2 sensors... again, if you have a Bosch P38, then they don't seem to like non-bosch MAF sensors (ask me how I know) or generic/cheap O2 sensors for some reason. I just replaced my O2's with genuine Bosch ones from Island 4x4 for about £55 each including VAT/delivery.

Purge valve for EVAPS on a Bosch is just down the LH rocker cover by the throttle body - and when engine is running you should be able to touch it and feel it 'buzzing'

Again, if GEMS - not sure where it is... and I think they are more tolerant to aftermarket/cheaper O2 sensors too..

what year is your tub?

Excellent post Marty. Thanks for explaining all that.

Yes, it is a 2000 plate THOR 4.0. I should have put that in the first post.

It was a cheap MAF I put in, but then the code was there before. So how do you know they don't like Bosch MAF's (since you asked me to ask).

Hopefully the cheaper parts will work though, I don't really want to be spending all that extra money on real (Bosch) parts if I can help it.

I put in a Bearmach MAF in mine as the Bosch one was faulty, and I didnt have the money for a genuine replacement. The Bearmach one worked, but the calibration on it is obviously not to the tolerances of genuine Bosch ones. It was constantly reading higher air intake than was actually going into the engine, so it was over fuelling and running rich all the time. The adaptive values eventually got to the point where they were at max and it started running rough at idle.

I finally had the money to buy a genuine Bosch one, and the air flow readings returned to normal, codes cleared, adaptive values reset and codes dont come back now.

O2 sensors - same deal basically. Ive read of others who have put cheap sensor on the Bosch systems and whilst they work, they just aren't to the same tolerances at the genuine ones, so the ECU uses its adaptive values to get it in spec, and then as they wear, there's no adaptation left, so I just starts running worse and worse.

My bank B sensor was starting to play up and I was getting misfiring at idle upon hot restart, bit only for about 30secs and on bank B.. Decided to swap both O2s for new Bosch ones and again its idling a lot better now and no rough running when restarting hot.

I honestly think its just a case that the manufacturing and calibration tolerances on the aftermarket stuff aren't as good as the genuine Bosch parts, and the Bosch ECU isn't as forgiving as the GEMS is when it comes to values being out and being able to adapt to them. It does try its best, but when it hits its limit, then you get the rough running happening.

My 0.02 anyway

Thanks for that.

So, looking for a cam position sensor. I'm guessing that's what is keeping the engine light on, and the ever so slightly rough running.

Having a look around, that is not a cheap sensor.

Anyone know anywhere better than this? Land Rover parts, spares, Land Rover accessories, all models - ERR6169

£171 for a genuine LR one. I'm guessing, after the above, I'm probably better off just getting a genuine one and being done with it. Or the britpart one at island 4x4 comes in at £120. Obviously £50 less, but not sure if it will make a difference?

Cam sensor very rarely goes wrong. I have heard that the connectors can get grotty and oil drips in them so they make a bad connection. Also if coolant gets into the connector/wiring then can cause corrosion.

I would look into that first before spending the money on a sensor... As I have heard of only a few cases where the sensor was at fault.

Ok. So disconnect and give it a clean then. Any guides anywhere on how to get to it / where it is? I have a copy of a workshop manual, but struggling to actually locate it.

xs2man said:

Ok. So disconnect and give it a clean then. Any guides anywhere on how to get to it / where it is? I have a copy of a workshop manual, but struggling to actually locate it.

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Look on front case just above crank pulley.

Thanks for that. Does it plug in at the back of the pulley then? Is that the right sensor? If so, that's gonna be a PITA to remove, and beyond my skill level probably. Well, beyond what I'm comfortable doing at least.

xs2man said:

Thanks for that. Does it plug in at the back of the pulley then? Is that the right sensor? If so, that's gonna be a PITA to remove, and beyond my skill level probably. Well, beyond what I'm comfortable doing at least.

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It goes into the front case and is held in position by a bolt.

Well, I'm pretty useless without pics. Can't seem to place it. This is what I thought it was :



Can anyone point to it in a picture? Or at least the area where I should be looking. I am not really a mechanic, and have almost no idea what things are called. Here are a couple pics I just took, but feel free to link others...

its between the water pump pulley and the crank pulley.

Yep, told you I wasn't great without pictures...

Is this it in here then:


I have traced a cable to something in there, but I wouldn't have a clue how to access it, it's a bit tight. The other place I was thinking was behind that big fan, but I don't have the appropriate tool for removing the fan to gain access.