35d got P0303 code

[mly229]

Hi all,

I'm reporting my 2012 x5 35 diesel (~85k mileage) with P0303 code read today. The car actually ran well yesterday, but "reduced engine output" warning ⚠️ appeared shortly and then disappeared. Today I got the code read at AutoZone, but very interestingly the guy told me the ignition coil was bad. I clearly know that Diesel engine does not have that thing.

Anyway, here is the detail definition from the printed out paper :" code P0303 indicates that cylinder 3 had too many misfires within a predetermined period of time"

I'm worried about the misfire might cause damage to the catalytic converter. Although the check engine light is not on. Any idea before I stop by the dealership or mechanic shop?

Many thanks.

[quick]

More than likely either a plug or the coil, get them checked out.

[Makaveli69]

only thing that can cause a misfire is a faulty or partially blocked injector.

[mly229]

Yes, after some research, I'm having the car for injector cleaning on Monday. Will get back for an update. Thanks.

[Makaveli69]

i was thinking today a faulty glow plug can also cause a misfire when engine is started cold.

[Juno01]

Originally Posted by quick

More than likely either a plug or the coil, get them checked out.

lol just being funny? 35d doesn't have these.

I would imagine the injector is the issue. Run ISTA/d, this will give you a much clearer picture.

[mly229]

Originally Posted by Makaveli69

i was thinking today a faulty glow plug can also cause a misfire when engine is started cold.

Thank you Makaveli69!

Here more input FYI: it does not fail the cold start, so far only two warning messages I got during regular driving (reduced engine output) and I couldn't actually feel any loss of power. The messages quickly disappeared and that's giving me speculation of a minor issue such as injector being clogged.

However, today at the dealership, they told me that they do NOT do injector cleaning for diesels... does that make any sense?

Everything is incredibly expensive in California! Dealer will charge $229 for diagnosis itself!

[mly229]

Originally Posted by Juno01

lol just being funny? 35d doesn't have these.

I would imagine the injector is the issue. Run ISTA/d, this will give you a much clearer picture.

Thank you Juno01!

Where do you think I can get ISTA/d test? I've tried AutoZone but they only provide very generic scanner. If I ask dealer to do this they will charge me $229...

[Juno01]

Originally Posted by mly229

Thank you Juno01!

Where do you think I can get ISTA/d test? I've tried AutoZone but they only provide very generic scanner. If I ask dealer to do this they will charge me $229...

You could try and pm the guy in this post for a download link. That will get you a vm and you'll need something like vmware or virtual box (free) to run it. You also need to buy a K+DCAN cable.

[mly229]

Originally Posted by Juno01

You could try and pm the guy in this post for a download link. That will get you a vm and you'll need something like vmware or virtual box (free) to run it. You also need to buy a K+DCAN cable.

Thank you Juno01, appreciate your help!

[mly229]

Update: today got 4 codes, but they are all "not present", so I'm a bit confused, anyway it seems to glow plug issue:

478E, not present, DDE: low-pressure exhaust-gas recirculation valve, plausibility

478F, not present, DDE: low-pressure exhaust-gas recirculation valve, plausibility

47C4, not present, DDE: low-pressure exhaust-gas recirculation controller, position control

4A5E, not present, DDE: Glow plug, cylinder 2, activation

Any ideas? Thanks.

[Juno01]

Looks like you need to check cylinder 2 glow plug. Make sure it's connected properly and if it is simply replace. They're easy to do.

Low pressure egr issue could be a vacuum leak, faulty egr actuator, faulty pressure converter, or clogged egr valve. The low pressure egr is connected to the dpf and down by the turbos. The pressure converter for the low pressure egr is under the intake near the glow plug controller I think.

[mly229]

Originally Posted by Juno01

Looks like you need to check cylinder 2 glow plug. Make sure it's connected properly and if it is simply replace. They're easy to do.

Low pressure egr issue could be a vacuum leak, faulty egr actuator, faulty pressure converter, or clogged egr valve. The low pressure egr is connected to the dpf and down by the turbos. The pressure converter for the low pressure egr is under the intake near the glow plug controller I think.

Thank you Sir!

Here is my update:
1) ordered parts: the glow plug service kit including everything at $341; the LP EGR valve at $220; and since I noticed the air filter could be an easy replacement under this task, I got it for $20, too.

2) My friend's friend is going to fix it for me because he works in a shop. I believe it is a fairly reasonable labor charge for 2.5 hours, so I will end up with $300 for the labor.

Waiting for parts in two days ~~

[mly229]

Originally Posted by mly229

Thank you Sir!

Here is my update:
1) ordered parts: the glow plug service kit including everything at $341; the LP EGR valve at $220; and since I noticed the air filter could be an easy replacement under this task, I got it for $20, too.

2) My friend's friend is going to fix it for me because he works in a shop. I believe it is a fairly reasonable labor charge for 2.5 hours, so I will end up with $300 for the labor.

Waiting for parts in two days ~~

Here comes the update FYI:

Fixed! So far the car ran > 600 miles and no codes came back

Thanks for all the help I received from here!