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P0420 - 2014, 1.0 Focus


BMNZ
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Hi,

 

Having a search on the forum it looks like this is a reasonably common problem but could use some advice. 2014 1.0 Focus, 80k miles. Went to head off to work earlier in the week an had the orange engine light come on.

I've got myself a code reader and Forscan and got the following:

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

P0402_small.thumb.jpg.04cb1b13ecc364c5bc4d4ff708be344c.jpg

 

I'm not sure whether it's a coincidence, but I've noticed that the coolant level has been dropping slowly over the last few weeks, maybe 10mm/week with the usual 3 x 60miles per week. Slightly worried it could be the head gasket, but I can't see any signs of milkyness under the oil cap, and the oil level doesn't seem to be dropping. I've just been out with the car idling for a while and again can't see any signs of where the coolant's going - it's a reasonably slow drop and I'm not sure it's even consistent. It's been run on 95 fuel for quite some time, currently at 80k miles.

For better or worse I'm still paying for the extended warranty, but the catalytic converter is now not covered due to the mileage limit (70k).

 

Before I take it in to a garage and they just turn around and say 'new cat' which I'm having to pay for, is there any information in the DTC report which might indicate it's not the catalytic converter itself? I can get some other readings if there's anything that would be worth checking. Is it worth trying to clear the code for now?

 

 

Thanks,

Bernard.

 

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Assuming you have the 1l ecoboost.

We have had faulty down stream lamda sensors which have been cheap from ford at around £30 trade some cheaper.

Difficult to diagnose without the right scope equipment, but if you are doing it yourself, if you can get it for reasonable money its worth a punt.

It will take 3 to 4 drive cycles for the code to return.

The code will return for either low or high oxygen outside the ecu specified range.

So its important you check for any cracks between the upstream and downstream lambda sensors, we get alot of aygo, c1, p108, p107 with this and have had 1 ecoboost with this also, and can be welded normally

 

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2 minutes ago, unofix said:

As unofix says, there could be other underline issues, im assuming you just have a minor coolant leak

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The Freeze Frame data does not throw up any red flags, though I would be more concerned about fixing the coolant loss first. It could be something simple like needing a new Pressure Cap on the Expansion Tank or a new Expansion Tank if it looks like it could have hairline cracks. You would not notice any visible coolant dripping with these problems.

You should be able to do Live Data Logging of the Coolant and possibly Cylinder Head temperature if you are worried about overheating. I would expect them to be in the 90 to 100C range with a fully warmed up engine whilst driving normally, a bit higher if driven hard.

Your Cat probably is past its best, but the code may be caused by the reasons that @Ecosport2019 said as well. If you go into Mode 6 Tests in FORScan there may be information for the Lambda sensors and Cat. The figures will be Double Dutch but if any of the Lambda Sensor ones are near their given expected limits then changing them may buy you some time although I would expect a different and specific code for them if they were faulty.

You can Live Monitor Lambda sensors with FORScan but the modern Wideband front ones do not behave like the old style ones so anything you read on Youtube about what to expect will not apply.

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15 hours ago, unofix said:

I might give that a try. Is the particular kit linked a reasonable one to get? I notice the instructions are to get it up to temp then high revs - from what I've read the coolant system ends up pressurised - are the instructions OK to follow for this or should it be used a little differently?

 

15 hours ago, Ecosport2019 said:

Assuming you have the 1l ecoboost.

...

So its important you check for any cracks between the upstream and downstream lambda sensors, we get alot of aygo, c1, p108, p107 with this and have had 1 ecoboost with this also, and can be welded normally

 

 

Yes, 1.0 ecoboost. I'm a bit limited in what I can do myself since I'm on-street parking on a semi-busy residential street where I am, party why I've paid for the extended warranty. The sensors would be covered, the catalytic converter no, but neither helps when the usual main dealer I bought it from and take it to has more than a month before the first diagnostics appointment (for no small fee).

I'll have a look at taking the shield off and check for cracks.

 

12 hours ago, Tizer said:

The Freeze Frame data does not throw up any red flags, though I would be more concerned about fixing the coolant loss first. It could be something simple like needing a new Pressure Cap on the Expansion Tank or a new Expansion Tank if it looks like it could have hairline cracks. You would not notice any visible coolant dripping with these problems.

You should be able to do Live Data Logging of the Coolant and possibly Cylinder Head temperature if you are worried about overheating. I would expect them to be in the 90 to 100C range with a fully warmed up engine whilst driving normally, a bit higher if driven hard.

Your Cat probably is past its best, but the code may be caused by the reasons that @Ecosport2019 said as well. If you go into Mode 6 Tests in FORScan there may be information for the Lambda sensors and Cat. The figures will be Double Dutch but if any of the Lambda Sensor ones are near their given expected limits then changing them may buy you some time although I would expect a different and specific code for them if they were faulty.

You can Live Monitor Lambda sensors with FORScan but the modern Wideband front ones do not behave like the old style ones so anything you read on Youtube about what to expect will not apply.

Is the coolant UV reactive at all? I'll run the Mode 6 tests.

 

 

Thanks.

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12 minutes ago, BMNZ said:

- are the instructions OK to follow for this or should it be used a little differently?

Follow the instructions.

You will probably find that it tells you to leave the filler cap off the expansion tank so that the system doesn't get pressurised, but that is me just guessing.

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14 hours ago, Tizer said:

... If you go into Mode 6 Tests in FORScan there may be information for the Lambda sensors and Cat. The figures will be Double Dutch but if any of the Lambda Sensor ones are near their given expected limits then changing them may buy you some time although I would expect a different and specific code for them if they were faulty.

You can Live Monitor Lambda sensors with FORScan but the modern Wideband front ones do not behave like the old style ones so anything you read on Youtube about what to expect will not apply.

I've been out for the Mode 6 results and got the following, I just had the ignition on and the car hadn't been started prior:

Mode_6_1.thumb.jpg.6403a60cd5bae80f98ec410f0a002ecd.jpg Mode_6_2.thumb.jpg.a023d1be4199cf9d82d69a1f5200fb52.jpg Mode_6_3.thumb.jpg.ef07237e4c00ba691c0a6a0339ac437c.jpg

Is it normal that Forscan would report the first Oxygen Sensor test as unknown?

The obviously reported problem is the 'Catalyst Bank 1'.

Also have the lower and upper voltage of oscillation check downstream sensor reporting values at the upper and lower limits respectively - not sure whether there's anything in that or is it expected due to the engine not running? Can/should the Mode 6 tests be run with the car idling?

 

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3 hours ago, BMNZ said:

I've been out for the Mode 6 results and got the following, I just had the ignition on and the car hadn't been started prior:

Mode_6_1.thumb.jpg.6403a60cd5bae80f98ec410f0a002ecd.jpg Mode_6_2.thumb.jpg.a023d1be4199cf9d82d69a1f5200fb52.jpg Mode_6_3.thumb.jpg.ef07237e4c00ba691c0a6a0339ac437c.jpg

Is it normal that Forscan would report the first Oxygen Sensor test as unknown?

The obviously reported problem is the 'Catalyst Bank 1'.

Also have the lower and upper voltage of oscillation check downstream sensor reporting values at the upper and lower limits respectively - not sure whether there's anything in that or is it expected due to the engine not running? Can/should the Mode 6 tests be run with the car idling?

 

The Mode 6 tests can be difficult to interpret and are only one small part of diagnoses, the good news is that you don't have a Misfire problem, which could ruin your Cat if you had one.

It is not unusual for FORScan to say unknown test and as far as I know you don't need to Engine running to access the stored data.

What I would do next is go into Live Data, bring up PID's for Vehicle Speed, RPM, Accelerator Position, O2S1 Current and O2S2 Voltage.

Go for a run and see if the O2S2 Voltage varies in the range of just over 0 to just under 1 when applying and releasing the Accelerator, preferably when moving and after the Engine is warm enough to be in Closed Loop, which should not take long. 

My gut feeling is that there not anything wrong with the Front Sensor or the Fuelling generally. I'm not sure about the Rear Sensor or Cat though.

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  • 2 weeks later...
On 10/29/2022 at 4:42 PM, Tizer said:

...

What I would do next is go into Live Data, bring up PID's for Vehicle Speed, RPM, Accelerator Position, O2S1 Current and O2S2 Voltage.

Go for a run and see if the O2S2 Voltage varies in the range of just over 0 to just under 1 when applying and releasing the Accelerator, preferably when moving and after the Engine is warm enough to be in Closed Loop, which should not take long. 

....

Haven't had much of a lot of chance to look at this between work and the weather, but just captured some data. Not sure whether I have got all the correct PID's (seemed to be 2 x TP?), but should FUELSYS be changing between Open Loop and Closed Loop like that? I think the car should have been warm enough.

The O2S11_IMPED seems to stay around 1.0 - is that the correct PID?

Drive.thumb.jpg.3ff2a4f238609410ba03fe465446d675.jpg Drive2.thumb.jpg.57a371d3645956e3cf7e5a10875dbc99.jpg

 

I did the gasket test last weekend. Certainly didn't go yellow, but did eventually go a sort of green colour after some time. Not sure if that's just expected if you run it long enough. I used the Reld kit linked by unofix - initially didn't seem to be getting any pressure build up in the system, but eventually realised the bung that comes with the kit was sealing on the outer-most ring of the expansion tank so any pressure was going out the inner port where the cap releases it's pressure. Had to cut the bung into more of a cylinder at the outer end so it would insert further and seal against the inner ring of the expansion tank.

Thanks again.

 

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1 hour ago, BMNZ said:

Haven't had much of a lot of chance to look at this between work and the weather, but just captured some data. Not sure whether I have got all the correct PID's (seemed to be 2 x TP?), but should FUELSYS be changing between Open Loop and Closed Loop like that? I think the car should have been warm enough.

The O2S11_IMPED seems to stay around 1.0 - is that the correct PID?

Drive.thumb.jpg.3ff2a4f238609410ba03fe465446d675.jpg Drive2.thumb.jpg.57a371d3645956e3cf7e5a10875dbc99.jpg 59.34 kB · 0 downloads

 

I did the gasket test last weekend. Certainly didn't go yellow, but did eventually go a sort of green colour after some time. Not sure if that's just expected if you run it long enough. I used the Reld kit linked by unofix - initially didn't seem to be getting any pressure build up in the system, but eventually realised the bung that comes with the kit was sealing on the outer-most ring of the expansion tank so any pressure was going out the inner port where the cap releases it's pressure. Had to cut the bung into more of a cylinder at the outer end so it would insert further and seal against the inner ring of the expansion tank.

Thanks again.

 

Once in Closed Loop it should stay that way. It may be that one or both the O2 sensors Heaters are not working, there should be PID's for that and I would have expected a fault code to have been logged as well.

Your Front O2 sensor looks ok to me, which means your Fuelling looks ok, but you didn't bring up the Rear one, O2S12. 

I don't think the Impedance value is useful, I would scrub that and bring up the O2S12 Voltage as well as the Heater circuits for both sensors. The two O2 Sensors should be almost mirror images of each other when driving, i.e., when the Current of the front one goes high, the Voltage of the rear one goes low. 

I don't know why there are two TP PID's, I always just use the Accelerator Pedal one for reference, the Throttle one is what the Throttle Plate has been commanded to do rather than what your right foot is doing.

I don't know much about the Coolant tests, @unofix probably knows more than me.

EDIT - If your Cat is shot then maybe that is why it is going into Open Loop. There is probably a PID for Implied Cat Temperature although I'm not sure what exactly it should be other than quite high.

Edited by Tizer
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5 hours ago, BMNZ said:

Certainly didn't go yellow, but did eventually go a sort of green colour after some time. Not sure if that's just expected if you run it long enough.

Hello Bernard, sounds like you had a bit of an issue getting a good seal to the coolant tank. I've had a similar problem before and just used a pair of mole grips to squash the overflow rubber hose and seal it. The liquid normally changes to a lime green not a proper yellow. It can take about 5 minutes to get a reaction it just depends how much exhaust gas is dissolved in the coolant. That fact that you got a reaction would indicate you have a leak. Possibly only the head gasket and not the failure of a cylinder or the actual block.

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If you still struggle to get a solid confirmation with your headgasket tester.

I would be tempted to leave the car sitting over night and remove the spark plugs in the morning, shine a pen light down the holes and see if you can see any damp in any cylinders.

Also have a look at the plugs to see if any look different from the others, usually one will look washed.

Does it misfire when its been left overnight?

Have you checked for damp under the front floor mats?

I would be checking again for coolant cust around the engine aswell just because they can be easily missed and hard to spot. The common places on these are.

The bottom of the radiator.

The metal pipes going into the front of the turbo .

The main thermostat housing on the head above the gearbox

The block thermostat under the exhaust manifold 

The hardest one to spot which is the one that was getting recalled years ago, is the one that leaks around the front of the engine between the timing belt cover and the cylinder head, had several of these go back to ford.

You need to use large and small telescopic mirrors ( very cheap to buy) with a torch to see any evidence.

The ideal scenario would be to use a pressure tester so you can see if the prssure drops after 5 minutes, this can sometimes also show a headgasket as it may misfire on startup after.

Goodluck

 

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13 hours ago, unofix said:

Hello Bernard, sounds like you had a bit of an issue getting a good seal to the coolant tank. I've had a similar problem before and just used a pair of mole grips to squash the overflow rubber hose and seal it. The liquid normally changes to a lime green not a proper yellow. It can take about 5 minutes to get a reaction it just depends how much exhaust gas is dissolved in the coolant. That fact that you got a reaction would indicate you have a leak. Possibly only the head gasket and not the failure of a cylinder or the actual block.

 

Before -> after

before.thumb.jpg.21acaf352e847a420f065732f1be71f7.jpg  after.thumb.jpg.30e8ff585e3588edbeab8b2a7addaace.jpg

Probably 10 to 15 minutes between.

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4 hours ago, Ecosport2019 said:

...

Does it misfire when its been left overnight?

Have you checked for damp under the front floor mats?

...

 

I've never noticed any misfires. I tried to have a good look at the pipes for the heater matrix a couple of weeks back and could find any signs of damp. Did they change the pipes at some point? It's possible I didn't get in far enough but I couldn't see the join that is prone to leaks. It has dual-zone auto cooling (DEATC).

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17 hours ago, Tizer said:

Once in Closed Loop it should stay that way. It may be that one or both the O2 sensors Heaters are not working, there should be PID's for that and I would have expected a fault code to have been logged as well.

Your Front O2 sensor looks ok to me, which means your Fuelling looks ok, but you didn't bring up the Rear one, O2S12. 

I don't think the Impedance value is useful, I would scrub that and bring up the O2S12 Voltage as well as the Heater circuits for both sensors. The two O2 Sensors should be almost mirror images of each other when driving, i.e., when the Current of the front one goes high, the Voltage of the rear one goes low. 

I don't know why there are two TP PID's, I always just use the Accelerator Pedal one for reference, the Throttle one is what the Throttle Plate has been commanded to do rather than what your right foot is doing.

I don't know much about the Coolant tests, @unofix probably knows more than me.

EDIT - If your Cat is shot then maybe that is why it is going into Open Loop. There is probably a PID for Implied Cat Temperature although I'm not sure what exactly it should be other than quite high.

I had another go. Hadn't realised I missed the S12 in the last captures. These captures have all the "O2" PIDs that are available. Two random slow to a stop and go from the captured data:

3_1.thumb.jpg.ddf4c9400749da593d12dc8f7b1632ea.jpg  3_2.thumb.jpg.722d0d389efeda6513fdaf470831cb19.jpg

 

Could be nothing (or normal), but I almost have a feeling I can hear a faint air hissing noise close in the engine bay while idling (with the AC off).

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1 hour ago, BMNZ said:

 

Before -> after

before.thumb.jpg.21acaf352e847a420f065732f1be71f7.jpg   23.89 kB · 0 downloads after.thumb.jpg.30e8ff585e3588edbeab8b2a7addaace.jpg

Probably 10 to 15 minutes between.

Not a massive reaction, but definitely a reaction. If you have any test fluid left I'd repeat the test. Leave the cap off the expansion tank and allow the engine to reach normal temperature before testing again. Just make sure that no coolant liquid gets in to the test kit or it can give false results.

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  • 3 weeks later...
On 11/13/2022 at 12:52 PM, unofix said:

Not a massive reaction, but definitely a reaction. If you have any test fluid left I'd repeat the test. Leave the cap off the expansion tank and allow the engine to reach normal temperature before testing again. Just make sure that no coolant liquid gets in to the test kit or it can give false results.

Bit of a slow update on this. At the time I did run the test a second time as you recommend - I have a feeling those pictures were the second run but I did get the feeling that eventually some of the hot coolant vapour makes its way in. Since then I have paid for a head test and they say it's OK (main dealer...).

This past weekend I had a go at taking the catalytic converter heat shield off but found one of the bolts was quite rusted in place. This is the one that also holds the 02 sensor clip:

 

Cat.thumb.jpg.2dad7cc331e33cf089b6cd5a165476eb.jpg

 

The base of the clip was so rusted it just broke off. Strangely it's only the one bolt that's actually rusted.

Assuming I can get it out I will need to buy a replacement bolt and clip. I can find a replacement clip OK online but not the bolt.  Looking on 7zap it's listed as:

HB1     1693233     Bolt And Washer Assy - Hex.Head    1.00     M6 X 11MM     from 21.02.2012, Focus 2011-

 

Is it possible it's been superseded by a newer part number?

 

I spent a bit of time cleaning off any oil etc that I could get to in the relevant coolant leak areas in the hope it might help with spotting any small leaks so will have another good look. It's a reasonably slow leak which is a bit of a blessing and curse as far as trying to locate it.

 

Thanks again.

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