Failed emissions test

It's that time of year MOT time, it failed the emsions test, i put a new cat and lambda sensors on last year to get it through the test.

When i got it home i put it on my scanner to check the lambda sensors on live scan they looked ok.

I scanned for any error codes and i get a P0340 code camshaft position sensor A circuit Bank 1 or single sensor, there are no warning lights on the dash.

Will a faulty camshaft sensor cause an high emissions reading, as it only failed on the emissions.

What would the symptoms of a faulty camshaft sensor be as it seems to drive ok.

It's the 1.8 k series petrol engine.

Depends on how clever the ECU is, I don't know with the MEMS system I'm afraid.

The point of the cam sensor is to tell the engine which rotation of the four stroke cycle the engine is in. If it can't determine that, it has to guess and will probably run more fuel through, more consistently than when it knows *exactly* where the cams are.

A lot of ecus switched to just regular teeth on the crank sensor to get the rotational speed, and a cam sensor to tell it where it is in the two rotations of the crank per combustion cycle, if that makes sense.

If it has to guess... it'll be off.

Is it definitely a hard fault, I'm quite surprised that the ecu light isn't on!

If the CMP sensor signal is missing, the engine will still start and run, but the fuel injection may be out of phase. This
will be noticeable by a reduction in performance and drivability, together with an increase in fuel consumption and
emissions.

I deleted the P0340 error code this morning then went to town and back, i've just retested and the code as not returned so far.

Is there a way to test the cam position sensor to see if it is faulty.

If it's not the cam sensor causing the high emissions reading i don't know what else it could be as it had a new maniverter, under floor cat, lambda sensors last year.

I also replaced the stem valve oil seals when when i did the head gasket towards the back end of last year.

I'm not sure where to go from here, is there any thing else i should be checking.

have you replace air filter

I replaced the air filter about 6 months ago when i did an oil and filter change.

Test for resistance by setting the multimeter to ohms,if resistance is infinite or 0 ohms, replace the sensor. Infinite resistance indicates an open circuit in the sensor, and 0 ohms indicates a shorted coil in the sensor.
The sensor must be removed for resistance testing with a multimeter

Using a voltmeter, measure the voltage from the wiring harness connector

I've just re scanned for fault codes and the P0340 fault code is back, i disconnected the camshaft sensor plug, it's a three pin plug, with the ignition on i get 12.5v on the outside pin, 11.69v on the middle pin and nothing on the other outside pin, this is with me holding the negative lead of the multimeter to car chassis and testing the three pins with positive lead.

I removed the camshaft sensor and tested each pin and get an infinity reading no matter which of the 3 pins i test, i used the 2meg ohm range.

What should the ohm reading be of a good sensor, i will get a replacement.

thanks for the info.

The camshaft sensor i've removed as bmw 1732566 and germany on it.

Will a bmw camshaft sensor work on the freelander 1, 1.8 engine.

....if you set the multimeter at 200k ohm it should be at 02.2 -02.1, it depends on the sensor...
I do not know if it fits that sensor bmw 1732566.....this is the genuine Camshaft Position Sensor - Freelander 1.8 Petrol - Genuine Land Rover at www.rimmerbros.co.uk

repeat ....depends on different values of sensor resistance ......do not work if it looks 0 or infinity

I got a replacement sensor today and fitted it, cleared the fault code, i'll have to see if the error code returns, i can't tell just by looking if it's effected my emissions, i'll drive it to work and back then do a scan, if all ok i'll take it for a re test.

The cam sensor i removed had bmw on the plug and the rover logo on round of the sensor near the bolt hole.

You can't test the sensor with a DMM because it's a hall effective sensor. You ne3d to back probe it and connect an osciloscope. It's likely to be a BMW sensor, the V6 Freelander cam sensor is also a BMW item
From memory the engine won't start if the cam sensor has failed completely. The engine will continue to run if the sensor fails whilst it's running.

What emission did it fail on? Was the replacement cat a genuine item? Often after market cats fail in very short order.

I think it failed on both hc and co, i didn't get a print out of the exact levels, i only got one sheet with the reason it failed, i had the exact same problem last year just failed on the emissions, this is the second after market type cat that it's had.

The original cat was a round tube about twice or maybe three times as long as the ones there selling now, these new cats seem to be short oval types, wished i'd kept my old one and just had a new bracket welded on were it had snapped.

Do they still sell the old type original cats, long cylindrical tube type, if so can you recommend where to get one.

I'm also using oil, i'm topping up by around a litre of oil a month, so this could be the cause if i'm burning oil, how does the engine burn oil, i replaced all the stem valve oil seals when i rebuilt the head last year.

digi said:

I'm also using oil, i'm topping up by around a litre of oil a month, so this could be the cause if i'm burning oil, how does the engine burn oil, i replaced all the stem valve oil seals when i rebuilt the head last year.

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A litre a month is a fair chunk, is it dropping it on the undertray?

Check under the timing belt end of the engine, the three seals on the front are usually pretty bad after a decade or so. Also pop the top cover off the timing belt (5 little bolts or so) and check that it's not getting in the timing case... like mine was.

Hopefully it's leaking through an oil seal somewhere...

If it isn't, that's quite a bad sign - you have an internal fault somewhere and it's getting in the combustion process - which could be what's causing the emissions fault.

I checked under the car and around the cambelt area and cannot see any oil leaks, so likely to have an internal fault then, i rebuilt the head last year so can't see it been the head.

I priced a new genuine cat up from the local LR dealership £847, that prices me out of getting one from landrover as it's more than the cars worth, are there any alternatives.

I took it to a local garage just to get the emissions checked before i took it for retest and it failed across the board.

I don't really want to sell it for scrap as it only failed on emissions but it's looking more like i will have to, i've got 3 weeks left on my old MOT to try find a solution.

digi said:

I checked under the car and around the cambelt area and cannot see any oil leaks, so likely to have an internal fault then, i rebuilt the head last year so can't see it been the head.

I priced a new genuine cat up from the local LR dealership £847, that prices me out of getting one from landrover as it's more than the cars worth, are there any alternatives.

I took it to a local garage just to get the emissions checked before i took it for retest and it failed across the board.

I don't really want to sell it for scrap as it only failed on emissions but it's looking more like i will have to, i've got 3 weeks left on my old MOT to try find a solution.

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A lot of the cats now require an activation procedure to get them through their MOT, I wonder if it was followed with your new one?

When fitted they're supposed to be run at high rpm for a period iirc, to get them hot and burn off a coating inside the cat to get it 100% up to speed. I have a tame MOT guy that sees it all the time, quite often the cat has never gotten hot enough to burn off the "this must be activated" sticker.

How about finding someone with a freshly blown head gasket/non repair and stealing their genuine cat for a few £?

Ordinarily I'd recommend inducing a vacuum leak, but these cars are MAP based and not MAF, so that old trick doesn't work

In the mean time run a compression test on it...

I started the compression tests after testing the 3rd cylinder my hose to the pressure gauge popped.

These are the readings cylinder 1 & 2 =150psi, cylinder 3=155psi, while i was looking at the 3rd reading i heard a pop and the pressure was released and a tear in the hose so could not do cylinder 4, i've ordered a new compression tester, the test was while the engine was warm maybe a little too warm it effected the hose.

If landyzone management don't mind me asking if anyones got a freelander there breaking or got an original catalytic convertor they would like to sell i'd be interested, it's the underfloor cat on a 2002 1.8 petrol engine.

digi said:

I started the compression tests after testing the 3rd cylinder my hose to the pressure gauge popped.

These are the readings cylinder 1 & 2 =150psi, cylinder 3=155psi, while i was looking at the 3rd reading i heard a pop and the pressure was released and a tear in the hose so could not do cylinder 4, i've ordered a new compression tester, the test was while the engine was warm maybe a little too warm it effected the hose.

If landyzone management don't mind me asking if anyones got a freelander there breaking or got an original catalytic convertor they would like to sell i'd be interested, it's the underfloor cat on a 2002 1.8 petrol engine.

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If you are burning a litre of oil per month, the cat is likely oiled up. A K series shouldn't burn 1 litre between service intervals. Is the correct grade of oil being used? Sometimes giving the engine a decent "Italian Tune Up" is often the only way to get pore quality cats through the Mot. I'd be tempted to replace the air filter and clean the plugs. Your compression is low which won't be helping it burn cleanly. Compression figures should ideally be 175 Psi, give or take 10%. You are well down at 150 Psi. You will need to identify the cause so remedial action can be taken.

When i removed the spark plugs to do the compression test, the plugs looked nice and clean not fouled up with oil or carbon that you might expect if i was burning oil.

I'm using 10w/40 semi synthetic, it says use 10w/40 in the manual.

I will do another compression test cold and warm when my new tester comes in the post, if i get the same readings i think it may be the pistons that are worn as i cleaned and lapped all the stem valves when i had the head off.

Nice and clean or really (steam) cleaned?