2005 T6 Throwing P0016 After Timing Belt Replacement

marcels · Post by **marcels** » 25 Nov 2020, 16:17

I had a competent independent repair shop replace the timing belt on my '05 XC90 T6, and when I picked it up I noticed idle to be rough. Turned around and returned it to him, at which time he cleared old codes and it seemed to improve. Took it home and by the time I traveled a few miles rough idle returned. Shortly thereafter CEL appears.

Brought it back and he he agreed to recheck everything. I asked whether he reset the VVT and he said they hadn't messed with the cam-gears/VVT adjusters - they simply brought the crank and cam-gears to where alignment marks matched and kept them in position while replacing the belt, pulley, tensioner, and water-pump. I also pulled the instructions from Vida, and those made no mention of having to adjust the VVT hubs when simply replacing the belt. I have however, read much on this site about the need to lock the cams from the rear and re-do the VVT adjustment...if that's necessary why doesn't Vida mention it???

In any event, the shop pulled the front cover off (miraculously no plastic nipple broken-off thermostat housing, which was also replaced during the service for that very reason). They confirmed alignment was correct. In the process of confirming, the ECM and TCM were removed again. When the mechanic noted smooth idle during the test drive, he questioned whether the ECM may not have had good contacts, or perhaps other demons simply exercised through the disassembly/reassembly process. {Being an engineer, I don't believe in demons}.

Drove it home and it seemed to run smoothly. My daughter, who now is the principal driver, took it to work and noted rough idle. By the time she returns home, CEL shows. Pulled codes using generic ODB2 and Torque app on my phone, and codes include P0016, P0026, P0300-P0306 (misfires on all cylinders), P0563, P2108, P2111, P2121, P2122, P2127, U0073, and U0167. "POWER SYSTEM SERVICE URGENT" also shows on the dash. Ugh. Called the mechanic, and plan and returning it to him on Friday (closed for turkey-day).

I have access to Vida, so I will be pulling "real" codes when I get the chance. Just thought I'd hit the sages up in advance.

Thanks for your help/interest, and happy Thanksgiving tomorrow!

-Marcel

Post by **RickHaleParker** » 25 Nov 2020, 21:10

marcels wrote: ↑25 Nov 2020, 16:17 {Being an engineer, I don't believe in demons}.

Of course not. Any rational person knows weird machine behavior is caused by Gremlins.

The P0563 is the battery/charging voltage. Get that first. Wrong voltages can create phantom codes. Check out the charging system and battery.

marcels · Post by **marcels** » 26 Nov 2020, 21:23

Hi Rick, and thanks for your interest!

Oh yeah, "gremlins"...the technical term used by IT "specialists" to justify the reboot that fixes everything.

I checked voltage and had a healthy 12.4v before firing, and 14.6v when running. Nothing appeared wrong with the battery or charging system. Pulled a boatload of fault codes using Vida today and then cleared them. Will re-check after a long run tomorrow morning, but after clearing I ran a good 20 miles or so in various conditions (fast/slow/braking/coasting/up/down hills), and no CEL appeared. Idle was smooth. Perhaps those were older codes the mechanic hadn't cleared.

One thing in particular he mentioned when I picked it up last time that worried me - he said they tried to fire and it wouldn't start, only to notice that the ECM hadn't been properly seated and latch fully secured. That did not sound right, and worried me that they may have damaged the ECM. Hopefully not. The reason I went with the indie shop was twofold: convenience (dealer is 30+ miles away), and price. Note to self: in future, just go to the dealer...I don't need these headaches!

-M

Post by **RickHaleParker** » 27 Nov 2020, 01:43

marcels wrote: ↑26 Nov 2020, 21:23 Oh yeah, "gremlins"...the technical term used by IT "specialists" to justify the reboot that fixes everything.

Analogical to "its a short" on the hardware side. Opens are way more common then shorts. High contact resistance due to oxidation is way more common then shorts. Every time I hear "its a short" I wonder if something is coming up short in the Wetware.

It is likely some or must of the that boatload of DTCs where artifacts. Some DTCs have Substitute values. Some of the Substitute values are to shutdown systems. It is possible that the artifacts shutdown so many systems the whole was not viable.

A loose control module would produce a boatload of DTS. Communication errors are one of the most common DTC types.

Post by **abscate** » 28 Nov 2020, 06:31

They screwed up the VVT. The P0016 code doesn’t come until after a drive cycle , I’ll bet you will find it’s pending in first start.

I bet they didn’t ccw clock the VVT correctly when they did the belt, but I don’t know the T6 that well

marcels · Post by **marcels** » 29 Nov 2020, 18:35

Update: since clearing codes no issues and daughter has put on ~30 miles, so fingers crossed...

-M