I have a P0015 code on my 2001 S40 1.9T. I changed the VVT and the sensor associated with the code. If I reset the ECU the car runs great for about three days, after which it reverts back to a retard timing and the CEL comes back on.
This makes me believe it's not a timing belt slip and the retard timing is due to an electronic failure.
Does anyone have any ideas of what else I could check? Someone at an auto parts store said it could be a vacuum leak... I'm lost at this point. any help would be appreciated.

 

some fault codes are "averaging" based meaning its the accumulation of errors over time, not the singular data point. Did you recheck the timing set up to make sure you are not one tooth off?

 

I have not checked it lately but will look at it again tomorrow.
Thank you for your help.

 

Can you be more specific about the parts you changed? When you say VVT, you replaced the gear itself correct? When you say associated sensor, are you referring to the cam sensor or the vvt solenoid? The solenoid is the one that is located on the same side as the gear.
If you have replaced the solenoid great. If not, follow the wiring for the solenoid as it makes its way across the top of the engine. That harness does get fragile over time and when the correlated plastic sleeve degraded the wires can easily be pinched when the plastic engine cover is screwed back on. Been there done that. I might be tempted to get a harness from the wreck yard or buy a new one if it’s condition looks pretty bad - you will get a good appreciation for it’s condition by looking closely at each coil connector and the wiring that feeds into it.

 

I have Changed the VVT solenoid with the associated filter. not the gear itself. I was afraid that that is what needed to be done next.
The sensor I changed was the camshaft position sensor. This is the sensor that is throwing the code.

Thank you for the tip on the wiring harness. I'm not sure If it is in that bad of shape. I followed all the connections and they seem to not have any cracks or pinches. But I have not tested all of the connections with a Multimeter.

I checked the timing on the engine and it is still in time.

Would you think the VVT gear needs to be changed?

Thank you for your help and response to my problem.

 

I have a new development.
I started my car and let it warm up. I then unplugged the VVT solenoid and the engine went to a smooth idle. When I plugged it back in, it went to a choppy idle again.
Is the idle controlled by the VVT solenoid? and does this sound like a bad VVT Solenoid or a bad VVT sprocket?

 

It sounds like the solenoid is moving the VVT gear to an incorrect position for idle. Especially if you are still getting the P0015 code after every 2nd engine start. When my car did this after a VVT gear change it was because the VVT gear was off by a few degrees. This was before I bought the cam holder tool and I was (stupidly) eyeballing my timing mark.

The 2nd time it happened to me was because the VVT gear failed internally. Now with your description of an idle change when you disconnect the solenoid I would suspect the VVT gear being in an incorrect position. Only a few degrees makes all the difference.

 

Thank you for your help.

 

Thank you for your input.
I reset my ECU and the car is running and idling fine now. I cleared the CEL and am trying to see if it stays off. I did this once before and it reverted back to the old way of idling and the CEL came back on after it finished its drive cycle. This is initially what lead me to think it was the Solenoid. If it reverts back again after the drive cycle do you think it could still be the gear alignment? If so, how would I check that without resetting the timing?
I Just warmed up the engine and listened to the idle after resetting the ECU. The car now idles fine and unplugging the solenoid does not change the idle.

 

To reset VVT gear alignment I'm afraid you are also into a timing job. Please keep us posted on how you make out. I too have been wrestling with a P0015 issue for about 18 months. Replaced solenoid, coil/solenoid harness, went to synthetic oil but code won't go away. I had previously replaced the VVT about 3 years ago so was very hesitant to replace it again but I'm afraid that's my next step. I was error free for two years so don't think I messed up the timing job 3 years back. If it were not for the emissions check coming up in October I'd be inclined to just live with it but they won't do the test if there is a CEL of any kind showing...stupid test, what a money grab!!!


The strange thing is the CEL came back 18 months ago after I did two things (and this may be just a total coincidence, of course):
1) I replaced the sparkplugs (thought maybe I damaged the already very worn harness so I changed it out)
2) I had switched to high mileage (non-synth) oil in the last oil change from just regular 5w30 (I've now gone to synthetic hoping some cleaning of small oil passages might happen)

 

I have driven the car for a few days and the CEL has not come back on.
Today I ran it through our local smog check and it passed. I'm not sure if resetting the ECU was the fix, but it did what I needed.

Thank you all for your help!

 

How do you reset the ECU?