E65 735I - (N62 32 VALVE - V8 ENGINE)

2003 BMW 735 • 12,500 miles

Hi Guys

I have a 2003 BMW 735Li E65 with the N62 32 valve V8 engine. The engine fault light comes on when the engine has been started from cold. I did a OBD scan and got the following fault code: -

'P1065 - Variable valve timing - time out, no signal, CAN Data Bus error'.

I clear the error and reset the light and the fault doesn't re-occur until the next cold start.

I fitted a new Valvetronic (VVT) ECU & voltage supply module 10,000 miles ago to cure a different problem with the valvetronic system so I'm hoping that's not the problem. The problem has only just started and the weather here in the UK has been very cold (near freezing) the past few days. Could the problem be temperature related?

There are 38 different BMW fault codes relating to the valvetronic system alone. I really wish I had bought a Mercedes!
December 17, 2011.

DrCranknWrench got it.
How is this one running Gtemco?

Dec 30, 2011.
Hi Again - I thought I would update you on the problem.

After a period of unseasonably mild weather during which time the problem didn't re-occur, I went into the electronics box and checked the wiring and connectors (no visible problems found); I removed the valvetronic ECU, main DME ECU & Integrated Supply Module and cleaned all of the connectors with electrical contact aerosol spray. After re-assembly and power up the car ran fine for a few days. Then after the car had been left standing for a few days during a particularly cold weather period, the problem returned with a vengeance with the car going into 'Limp Home' mode. Not only am I getting the same P1065 code. I am now getting a related P1061 code 'Variable Valve Timing, Bank 1 - Limp Home - circuit malfunction'. In addition I am getting other failure messages from the DME, e.G. 'ACC Failure - drive with caution' - 'DSC Failure - drive with caution'.

I am now beginning to suspect the main DME ECU and the fact that the problem seems to be temperature critical. Note: - 1. The original problem back in December started after the car had been left standing in very cold weather and disappeared when, for a few days, the weather became very mild. 2. When the temperature under the hood is raised after 10 - 15 minutes of the engine running, then I can switch the engine off, wait for a minute, re-start the engine and the problem disappears (almost like doing a 'warm re-boot' on a computer) 3. The problem only returns after the car has been left standing in low temperatures (overnight in this case). 4. During problem periods I notice a slight 'roughness' in the engine's running and when I detect a definite 'smoothing out' in the engine, I know that's the time to pull over and perform the 'warm re-boot' previously described, confident that the problem won't re-occur for that driving session.

As you know from earlier in this thread, the car is running a valvetronic ECU from a donor vehicle and ran for 10,000 miles with no problem. Could I install the main DME ECU from the same donor vehicle (identical model and year)? Or would data conflicts prevent it from running? Hell.P!

PS. I was almost at the point of giving up on this car and scrapping it but the 'mule' in me has picked up the gauntlet, determined(for now anyway)not to be beaten. Another donation to this great website is on it's way.

Jan 14, 2012.
Go ahead and give the donor car ECU a try. Remember that it will take awhile to "get used to" the conditions and sensors in the car.

Jan 15, 2012.