2006 cadilac dts valve cover replacement

Could be as simple as a bad relay. I would start by replacing it with a known good one of the same type.

I'm not familiar with your vehicle (I'm in the UK). However, the EGR valve is usually connect to the air intake.

Look for a 'unit' that is connected to the air intake via a tube.

Here's a link done with a general Google search for '2006 Cadillac DTS egr'. Hopefully you will recognise your own egr valve amongst the images:

2006 Cadillac DTS egr Google Search

BMW, 3.0i has two Timing Chains. Primary Timing Chain can be
reached by removing the Harmonic Balancer. Lower Timing Case Cover. Vanos Adjusting Unit. Secondary timing chain replacement will require removal of several components and Vanos Adjusting Unit.

Usually you just "Squeeze-in" on the plastic dome sides to remove the cover, and then you will see the buld - some are push-in-twist 1/4 right and pull out, others may pull striaght out.

Here's a link to your timing marks. Repair Guides Engine Mechanical Components Timing Chain Cover Chain...

If the problem is the solenoid not releasing the door, you might try to access it from within the trunk.

2006-2007
FRONT Soft ride & sport suspension, 118 ft-lbs/160 Nm;
heavy duty suspension, 170 ft-lbs/230 Nm.
REAR Models with FE7 suspension 147 ft-lbs/200 Nm.

The metal air caps cause an imbalance on the tire, plastic is far better without throwing the rim out of balance.

Re-seat the connector at the back of the bulb/ unit. if you shake the harness and light flickers then the contact,or wireing has a short and can easily be fixed with a new connector or splicing the bad wire.

Check your oil first. I guarantee your car burns oil and it may be very low on low. The ticking may be a lifter starved for oil or one that has debris in or on it. The timing chain usually makes a "slapping" sound when it gets slack in it from lack of tensioner adjustment.

A sure fire way to check the timing chain if you are concerned is to take off the valve cover (also a good time to replace the valve cover gasket). Then you can see the chain and feel and see if there is any slack in it.