 | Home > Puma (Tdci) > OBD Code p121C of codes |
 
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| Crofter Member Since: 19 Feb 2015 Location: Peterhead Posts: 169   
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Sorry guys I should have searched harder it is a fuel injection problem. It has been covered here on this forum.
I am not sure how confident I feel about this area. Are there any simple checks to narrow it down? |
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15th Feb 2023 11:12am |
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| hornet Member Since: 04 Jan 2010 Location: Western Europe Posts: 361 |
What mileage are we talking about?
The first thing I would do is changing the fuelfilter if the status is unknown. But it is not responsible for your code! The second thing you can do is to disconnect the plugs of the injectors one after the other while the engine is running and check what happens. Maybe it will become clear which injector is causing problems. Edit: Another option (maybe the new second step) could be replacing the overpressure-valve at the rail. |
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17th Feb 2023 2:19pm |
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| Crofter Member Since: 19 Feb 2015 Location: Peterhead Posts: 169
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The defender is a 2009 with 57000 on the clock.
Since the code was cleared I have not had the engine going into limp mode, not sure really what is going, on here. The fuel filter was changed at the last service which was June\July 2022. Been underneath cannot see a weep on the fuel line that is visible. Your options sound good and I will try to investigate at the weekend. Thanks. |
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17th Feb 2023 3:04pm |
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| hornet Member Since: 04 Jan 2010 Location: Western Europe Posts: 361 |
Have you made any progress, found the cause?
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13th Mar 2023 4:35pm |
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| Crofter Member Since: 19 Feb 2015 Location: Peterhead Posts: 169
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Nothing makes sense.
I reset the fault and P121C, cleared it. I thought I had 2 problems one was at about 3000 revs the engine went into limp mode. This has never come back on. But P121C I found on here was something like crank unbalance or leaking injector. But since the reset it has run well although it’s waiting eBay delivering some oil as it’s low. It has been starting easily enough also. |
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13th Mar 2023 4:54pm |
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| NoLimits Member Since: 29 Dec 2022 Location: Somerset Posts: 58 
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Hi,
I believe that the code P121C for a Ford engine can be either: A faulty fuel injector The fuel injector harness is open or shorted Or the fuel injector circuit has a poor electrical connection |
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20th Mar 2023 12:00pm |
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| Crofter Member Since: 19 Feb 2015 Location: Peterhead Posts: 169
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Thanks that’s interesting.
Are the codes different between Ford and Landrover. Since clearing the code I have not had any problem. So it might be a poor electrical connection in the injector circuitry, but could be a poor injector. Is that your take on it. But by the sound of it I have an electrical fault. Thanks |
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20th Mar 2023 12:28pm |
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| Ianh Member Since: 17 Sep 2018 Location: Essex Posts: 1972
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Like Hornet my initial view would have been a faulty injector or injector seal, or like nolimits points out an injector wiring or connector issue, but given once the code was cleared all is running ok then do you still have the starting problem if parked uphill ?
I’m wondering if you had some air in the system after fuel filter change, or the filter was not sealing correctly, letting air in. This could possibly have caused the P121c code, which would have triggered limp mode. Now the code is cleared and if the filter is sealing and no air in system then that is perhaps why all is now working ok. Was the fuel filter a gen LR one as some after market ones can have sealing issues. |
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20th Mar 2023 1:16pm |
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| Crofter Member Since: 19 Feb 2015 Location: Peterhead Posts: 169
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On the uphill issue I have not tried that for a while, I will try that tonight, overnight.
Starting has been no problem and the going into limp mode at around 3000 rpm does not happen. The last service was about 10 months ago or 4-5k approx. I assumed he had used LR parts I will check on that. The service was done by a local country garage. You have given me some good points to look at and investigate. Thanks for these points. |
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20th Mar 2023 3:37pm |
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| Crofter Member Since: 19 Feb 2015 Location: Peterhead Posts: 169
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Ian the uphill starting issue didnot occur. So I am hoping that is cleared. |
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21st Mar 2023 5:15pm |
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| Ianh Member Since: 17 Sep 2018 Location: Essex Posts: 1972
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Good to hear all is working ok now,
I suspect either some air in the system or more likely a slightly dirty injector. So I would add a bottle of Forte Diesel Specialist Injector Cleaner to your tank, https://www.forteuk.co.uk/product/diesel-s...r-cleaner/ Then on each subsequent tank fill use some millers diesel power ecomax , you only need circa 20mm per full tank https://www.millersoils.co.uk/products/diesel-power-ecomax/. This should clean your injectors and keep them clean. Plus the millers raises cetane level of diesel so engine runs better at only a couple of extra pence per litre of diesel cost. |
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22nd Mar 2023 2:10am |
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| Crofter Member Since: 19 Feb 2015 Location: Peterhead Posts: 169
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Ian I did use the Miller oils product.
But not until the fault came back. Seems to be running as good as ever now. I put a double dose in the tank to start with. Again today followed up with a single dose. The fault had cleared for about a 1000 miles after the last time but I notice a difference now. Thanks |
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15th May 2023 3:21pm |
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