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Discussion Starter · #1 ·
This is NOT a thread to ask questions on.

The purpose of this is for the more experienced members here to post common Omega related problems and solutions.

Thanks. :)

Discussion Starter · #2 ·
What is the paperclip test I keep reading about?

On petrol engined Vauxhalls up to approx 1999 you could flash out fault codes stored by the ECU. If your orange engine management light (EML) came on for more than a few seconds, it would mean there was a fault code stored.

Here is how to do it on the Omega.

Try doing this with the engine running if possible (to avoid a false code for crank sensor). Not always possible, sometimes it will only work with just the igntion on.

The diagnostic port (the thing that Vauxhall will use with a tech II reader and charge a small fortune for the same information!) is under the steering wheel, on the left hand side. Undo the catch and you will see lots of fuses on the right, and the the diagnostic port on the left. It is mounted vertically and has 16 pins.

You need to short pins 4 and 6. This is where the "paper clip" comes in useful, although any piece of wire will do.

Pin 1 is located top right as you look at it. Pin 2 is directly below, then pin 3, pin 4 etc.

This will cause the EML to start flashing. Don't panic if you don't catch the number of flashes the first time.
Each code is repeated 3 times.
Once it has completed the cycle, it will start again.

First code is always 1 flash, pause, 2 flashes = 12. Diagnostic startup.

A full list of the codes and their meaning can be found here:

What ecu does my Omega have?

You need to know this so you can read the results properly.

2.0 4 cylinder Omegas have the Siemens Simtec 56.0/56.1 ecu
2.5 & 3.0 6 cylinder Omegas have the Bosch Motronic 2.8.1/2.8.3 ecu.

Once you have your results, post them up on the forum and we will advise. :)

Please note: After 1999 the chipsets were altered so it was no longer possible to flash the codes out this way.

Club Barge
3,467 Posts
Oil in Coolant

If the car seems to be running normally without adverse overheating, but you begin to show signs of oil mixing with coolant, DON'T PANIC. It is likely your oil cooler is on it's way out.

A sludge in the header tank can also point to this. It does not always mean Head Gasket failure.

See :-

Head gasket failure is rare on the V6 engine, but often a failing oil cooler is mis-diagnosed as head gasket failure (complete with very scary repair quote!)

Simple rule of thumb:

Oil mixing with water in header tank= Oil cooler

Water mixing with oil producing LOTS of mayo around oil oil filler cap = possible head gasket problem.

Small amount of mayo in oil filler is not uncommon when the car is doing shortish journeys and nothing to worry about.
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Club Barge
3,467 Posts
Autobox Weirdness

If your box starts to change oddly, drops out of gear or feels jerky....

1 - Check fluid level with engine running at normal temperature and on a FLAT surface, it should be just at the top of the filler hole. This is located on the side of the gearbox.

2 - Change the fluid and filter.

See :-

We recommend fluid changes every 60k or so, to keep the gearbox in good condition.

Club Barge
3,467 Posts
Oil leaks into plug wells on the V6 models

The most common cause is cam cover gasket failure. The reason for the cause is usually blocked breathers.

Changing the cam cover gaskets is covered here :-

Cleaning the breathers on the V6 is covered further down this FAQ section.

*It is essential that cleaning the breathers is undertaken after you have changed the gaskets.

After affects of the oil leaks can be:-

Misfires, this is due to the plug leads drying out and breaking down. Replacement is covered here:-

Discussion Starter · #6 ·
Cambelts. What is the correct service interval?

On ALL petrol Omegas the cambelt kit (belt, tensioner, pulley) should be changed every 40k/4 years
(whichever comes sooner).

Do not just get the belt changed (whether DIY or garage, ensure the receipt is for the full kit).
It is the tensioner that usually fails first.
On a multivalve engine, this usually means you replace the engine! :(

If you have just bought the car and you do not have a receipt for a full kit change, budget for this to be done ASAP!

Club Barge
3,467 Posts
2 litre idling problems

This is a questions that comes up from time to time. The 2.0 can sometimes idle erratically, usually cutting out at the worst possibly moments, on junctions, in traffic, or in severe cases, when changing gear!.

The problem is usually nothing more sinister than a gummed up idle control valve and associated assembly.

The cause of the problem is having the breather from the crankcase exiting very close to the main throttle body. Oil and tar deposits collect, gumming up the valve which in turn causes these problems.

Fitting a fire trap can help to a certain extent, as this stops a certain amount of the deposits finding their way into the air flow. See here :-

However, the above work goes well with cleaning the entire assembly. The problem commonly affects Vectra owners, whose cars use the same engine as the 16 valve 2.0 Omegas. A fix for this is described in detail here :-

The important thing is to ensure that the small drilling in the throttle body is clear and that everything else is as free from dirt as possible.

Club Barge
3,467 Posts
Cracking Doors

A particularly nasty ailment that can affect the Omega and one that is a common question on this forum, is the dreaded death crack coming from the doors. If left un-attended the bracket welded to the A or B pillar (depending on whether it is the front, or back door affected) will tear. This is not good and messy to repair.

A user of this forum has documented an excellent How To covering the procedure, shown here:-

I have found that regular greasing of this area, with the weekly application of WD40, can help stop the problem becoming bad in the first place. Applying grease to the hinges every 6 months helps keeps things in fine fettle also. A small amount of grease in the lock latch units helps these stay supple and free moving also.

Premium Member
1,089 Posts
Oil Thread ***Alert***

Oil Change And What The Best Oil Is To Use

As there have been so many threads created on this forum now just on the oil subject Semi or Full Synthetic, I thought I would write something up for new users to look at for assistance instead of starting a new thread.

The recommended on this forum is to use no less than 10w 40 Semi Synthetic oil and to always change the filter when doing an oil change.

Now if you are after more details on this subject, hit the Search this Forum button, on the right hand side of the page and just type Synthetic in the bar provided hit Go, this will bring countless threads all with this word in and the majority of them are about engine oil types and recommendations. (See picture below)

This search function can be used throughout the forum, to aid in searching for whichever subject you are looking for.

Hope this helps everyone.


Discussion Starter · #11 ·
Steering pulls to the side or knocking noises over bumps?

Firstly, steering pulling to the side could be many things. Tyres, tyre pressures, wishbones, steering idler, suspension struts or even accident damage.

Knocking or clunking is usually the drop links and or wishbones. Don't eliminate everything else. A broken spring can often sit at the bottom of a strut and clunk over pot holes without falling out. Also A bumper not tight can sound the same!

Easiest thing is to eliminate the worst things first and check the easiest as well. So, get underneath with a torch and look for obvious signs of chassis legs being bent or crumpled. Look for fresh paint or welding. Is one side of the car much cleaner than the other?

Next tyres. take the wheel off and look at the wheel for damage and especially the tyre. Look for bulges, particularly on the inside edge. Look at the tread carefully and check for uneven wear or cuts,splits etc. Check the tyre pressures. As a general guide 30-32psi all round seems about right, but check your handbook. It does depend on load as well.

Now check the steering idler. Jack up the left front and rock the wheel from left to right whilst someone looks at the idler. Is there movement and play?

Wishbones. Get a breaker bar and try to move the bushes. There should be virtually no movement like this.

Drop links, examine the rubber for age related damage and splits.

If you find uneven tyre wear and/or the sterring wheel is not centred, chances are your tracking is out. Get 4 wheel tracking done. This will ensure the steering wheel is centred properly as well as the tracking set up. If you find the wheel isn't centred afterwards, go straight back and insist they put it right and don't take no for an answer. The Omega isn't special, different or difficult. In fact the tracking is particularly easy to adjust on these, so make sure they do it right.

Discussion Starter · #12 ·
One touch windows and multi position sunroof (where fitted).

On Omegas (also Carltons and Senators) the windows have a one touch function for operation both up and down with retraction sensors.

The sensors are a very sensible safety feature where if the motor feels resistance when raising the window, it stops and reverses the window a few inches. These work whether you have the one touch activated or not.

If you have disconnected the battery, the windows and sunroof will go back to basic settings, ie. keep finger on button to operate window.
Also the sunroof control probably will not work.

To re-activate one touch, with the window closed, simply press and hold the button as if you were closing the window for 2-3 seconds. If it quiet you may hear the relay click. Repeat for each window.

The sunroof is slightly different.
With the sunroof closed, push the controller in and hold for 2 seconds.
Do the same with the dial in the fully open position and in the tilt position.
Sunroof is now reset. :)

Club Barge
3,467 Posts
Have my Head gaskets Failed? V6 Owners

See the above flowchart, PM me with any suggestions.

JCT - Original creator of this lovely flowchart :)

Club Barge
3,467 Posts
Omega Part Numbers

Omega Part Numbers

This may be of use. I shall update each time a part number is referenced, just so we have an area to refer to.


Pollen Filter up to 2000 P/N 90510338 - standard white
Pollen Filter from 2000 P/N 91158514 - active charcoal black
4 Pin brake switch P/N 9149766
Non Cruise brake switch P/N 9149765
Dash Bulbs P/N 9195062
Door Solenoids Pre mini-facelift: P/N 90449074
Door Solenoids Post mini-facelift: P/N 90493702
90513305- Description is "CLIP,UPPER PART,PROTECTIVE MAT FIXING (Floor mat fixing screw thing)
90397444 (4 in a pack) (the bit that the Floor mat fixing screw screws into)
99 2.5 discs and pads 93175466.
Rear Heated Seat Relay P/N 90 274 652 61 201 601
90 494 953 Blue - are fuel pump relay, and fuel injector relay.
Y1011857 - Speed Control Unit
90 494 187 - Windscreen Wiper Delay
90 459 640 - Water Cooling/AirCon - x2
90 060 264 - Turn Signal/Immobiliser Relay
90 491 314 - Air Injection Pump System/Water Fan
90 450 169 - Water Cooling Fan
90 450 481 - Water Pump Relay
86 447 09 - Auto Transmission selector lever seal
90 566 947 - Heater Bypass Valve, V6 models

V6 DIS Packs
0 221 503 002
0 221 503 010
0 221 503 017

ABS Modulators

1 UNIT,CONTROL,ABS (BOSCH X25XE,X30XE R1000001 -V1006448 1 (90444662) (12 37 645)
0273004049) (NLS.- USE
90541367 62 37 575)
(90444662 )

1 UNIT,CONTROL,ABS (BOSCH X25XE,X30XE V1006449 -V1999999 1 90541367 62 37 575

2 UNIT,CONTROL,ABS (BOSCH X25XE,X30XE W1000001 - 1 9117171 62 37 698

ENGINE ITEMS 4cyl and V6

For Rocker gasket job
Rocker gaskets: 90511451
O-rings: 90411826,
Gasket, Inlet bridge to head: 90501652
Gasket, Inlet to Inlet bridge: 90501653
Gasket, Inlet to Plenum O rings: 9118135
Sealent, Black (not the Green stuff!): 90485251

For Oil Cooler
Heat Exchanger (Stainless Steel) 13 101 668 90 06 313
Banjo bolt 90 424 578 13 36 977
Sealing 09 163 307 15 03 301
Seal ring 11 076 852 20 91 055
Seal ring 90 409 175 06 50 760

2.0 Cam/Crank Sensors
90458252 (sensor between the cams)
24445139 (the other sensor)

V6 Crank sensors
the square one 90492006
the rounded one 90492061

20SE - X20SE Engines had air box No - 90448355
X20XEV Engines had air box No - 90448355
X25XE - Y26SE - X30XE - Y32SE engines had air box No - 90448352

90564580 - Wiring harness for use with a 120amp alternator same as the c25xe engines and the 3.0l
90566289 - fuel injection harness for use with automatic transmssion
90566288 - fuel injection harness used for manual transmission


72119076 and 72119077 Front Struts, 2.0 and 2.2 with non sports set-up

Rear Diff

1 DIFFERENTIAL,ASSY.,38/9RATIO X25XE,Y26SE -11034911 1 90523884 4 03 111

1 DIFFERENTIAL,ASSY.,38/9RATIO 11034912 - 1 24414546 4 03 006

2 DIFFERENTIAL,ASSY.,37/10RATIO -11020494 1 90465557 4 03 103

2 DIFFERENTIAL,ASSY.,37/10RATIO 11020495 - 1 24414542 4 03 002

3 DIFFERENTIAL,ASSY.,39/10RATIO -11020912 1 90470842 4 03 109

3 DIFFERENTIAL,ASSY.,3.9/1RATIO 11020913 - 1 24414544 4 03 004


1 DIFFERENTIAL,ASSY.,37/10RATIO -11036942 1 90465558 4 03 102

1 DIFFERENTIAL,ASSY.,37/10RATIO 11036943 - 1 24414543 4 03 003

2 DIFFERENTIAL,ASSY.,39/10RATIO -11019833 1 90470843 4 03 110

2 DIFFERENTIAL,ASSY.,39/10RATIO 11019834 - 1 24414545 4 03 005


4 x 9195961 (repair plate)
4 x 13104167 (torx headed screws)
2 x 90462823 (plastic bushes)

door stay mods, stops cracking door syndrome

Club Barge
3,467 Posts
Omega Air Conditioning

There has been a lot of posts lately about the Air conditioning and climate control systems in the Omega. The system on my car is fully working, charged last year with new drier and compressor, so I am using this as a basis of a working system.


If the interior of the car is swelteringly hot, I have found that it takes a while for the system to prime and get the temperature down. This is normal. I have found that opening all the windows for a mile after starting allows most of the heat out, and allows the air conditioner to start working, close all windows after the mile and it should cool much much quicker.


Easiest way to check, turn on the engine, put the aircon/climate on, set to full cold, open the bonnet, shut the door and open the bonnet. Look down at the compressor, is it spinning? YES is a good sign. Also look at the large aircon pipe, this will start to gain water droplets if it is working, and will be icy cold to the touch. The air coming out the vents should be cold.

Weak Spots

* Condensor is a weak point on the system, they have be known to leak.

If the compressor is not spinning, check in the following order.

1 - Bridge the low pressure switch, if the compressor cuts in, the problem could be low refridgant, or one of the other causes.
2 - Run bridge the terminals on the radiator fan sensor, if all the fans come on, that's good. The problem could be linked to a switching relay that causes the fans to come on low speed for the climate control.

I would never touch or break into the air con circuit though, this is best left to a professional.

I would haggle for the following services.

vac out, fill with nitrogen or other inert gas and have pressure tested after an hour, drain, replace drier then fill with refridgant and UV leak detector, make sure they also top up the air con compressor system oil, this is essential.

Every 2-3 years for an aircon service should be fine.

Contrary to popular belief, use the system in the winter. This is essential to ensure long life of the seals and the system as a whole.

WET FEET - Answer courtesy of Old Crusier, thought it'd be useful in the FAQ

When you have checked that the scuttle is not blocked, and the matrix isn't ruptured, on 1999 to 2001 models, Vauxhall issued a service bulletin.

There was an issue with some models built between 1999 & 2001 with water ingress in footwells, something to do with a foam ring not fitting correctly at a joint behind the console relating to the A/C condensation drain tube, so will only occur when A/C is on, following Vx Info' may help and hopefully cure the problem.

Replace and adjust foam seal ring and install an additional slim seal washer.
1. Loosen and draw back centre console.2. Remove old foam seal ring. 3. Install and adjust new foam seal ring Press down the seal lip of the drain funnel, push the foam seal ring between drain-tube of AC-housing and slip it onto the drain-tube. Install new slim seal washer. Press down the seal lip of the drain funnel and slip the slim line washer over the drain tube of the AC-housing. Position the slim line washer above the bead at the lower end of the AC-drain tube.4. Check/adjust the correct lining of drain funnel with foam seal ring. Important: Not visible back side of drain funnel has to fit also 5. Attach centre console. Spare parts: Part-No.: Foam seal ring 24 455 185; Slim seal washer 09 240 180

Club Barge
3,467 Posts
Engine Photos - V6

Engine Photos - V6

The following photos have been found by JasonH , the question of what is where on the V6 pops up from time to time, the links below will hopefully help to locate various bits for the future.


Discussion Starter · #17 ·
In the past I have had the following

Condensor leak

Broken pressure sensor wire

SO it is worth checking properly

Flibblemeister General
1,328 Posts
Omega MY98 onwards ABS/ TC lights on; speedometer not working

The first thing to try in this situation is to check and clean the ABS sensors on each wheel (especially the N/S/R which is where the speedo feed comes from)

If after doing this the lights are still on and the speedo isn't working then ideally find someone with a tech2 or similar system and see if the computer can communicate with the ABS ECU attached to the hydraulic modulator.

If it can't communicate with the ECU then the problem almost certainly lies with the ABS ECU itself. Unfortunately a very common problem, especially on MY98> versions (VIN W1000001 onwards)

Vauxhall charge about £650 to do the job all in with the unit itself costing about £300.

It is not a nice job to fit and requires patience amongst other things.

To access the unit you need to remove: (based on a 1998 3.0 MV6)

-Engine relay/ ECU box
-Top radiator hose
-Coolant transfer pipe (thermostat feed pipe) (for clearance)
-Top plenum (optional but easier to locate the transfer pipe properly with it off)
-PAS pipe from top of pump for clearance
-PAS reservoir (ideally but can be moved out of the way, but will stretch pipes.)
-Undo all engine wiring loom round connectors from rear edge of battery tray.

When you are removing the PAS components note that the reservoir is directly above the ABS module, so make sure the fluid doesn't pour on the unit when you remove it.

The main top electrical plug on the ABS ECU has a sliding retaining clip. This slides towards the outside of the car, and is quite fiddly to get to even with all the bits out. You need to slide it as far as it will possibly go to allow the plug to come off.

Underneath the module is another, small, plug which has a more conventional plastic clip. Remove this and make sure the wire doesn't disappear into the bowels of the engine bay.

The ECU is held to the modulator with six small torx screws. The screws are well set back and in small apertures as can be seen from the picture below so you will need torx bits at least 2" long to actually reach the bolts. Also bear in mind with the unit on the car you can only actually see the top two screws. The rest are all done by touch, and a lot of luck.

To undo the bolts I used an angled screwdriver bit holder as there is extremely limited access to the bolts. See the following link:

Once all the screws are undone (You may lose a couple but the new unit should come with new screws) the unit should just come straight off. Be careful not to get any dirt or fluid on the exposed section of the ABS modulator, and give the surface where the module meets it a gentle clean.

Refitting is then reversal of removal to quote Haynes, but fitting the screws is much more difficult than removing them. Gently fit the top two to hold the unit in place. What I did next was to use insulating tape to stick the screw heads to the torx bit then very gently try and locate them. This will take many tries and a lot of swearing. The advantage of insulating tape is that when the screws are tight the tape will slip off of the bolt.

Once all six bolts are in place reconnect the plugs, refit the coolant transfer hose (replace the two rubber O rings), refit the plenum if removed (replace the manifold to plenum seals).

From then on refit as normal.

When that is all done the speedo should work again and the ABS light will go out.

After fitting the module will need to be set up on Tech 2 or a similar system to configure the module to the car. This will then put the TC light out and reset any running problems after fitment of the new module.

This is not a job I would wish on to anyone, but my point here is that it is possible to do it as a DIY job, even if it is a pain in the arse, and you will save yourself £300 - 400 worth of labour.

Club Barge
3,467 Posts
Why are my Cam Cover gaskets leaking on my V6?

Possibly due to an increase in crankcase pressure due to blocked breathers.

I completed the cleaning on mine back in early March 2006. Here's how I did the job, just for future reference.

Also, check this thread which shows the route that the breathers take in the ECOTEC breather conduit.

1 - Remove the scuttle.
2 - Remove the plenum chamber, as this will need a clean as well.
3 - Using carb cleaner, or paint thinners (work just as well) clean the plenum, around the throttle body especially.
4 - I then removed the black ECOTEC bit (1 torx bolt) and prised this off the plenum, blast it through with either some carb cleaner, or a combination of thinners and tap water/the high pressure attachment on a hose pipe.
5 - Blast the ECOTEC bit through with WD40, just to dry it out.
6 - Remove the big black, dual outlet breather pipe, which is located on top of the breather box.
7 - Attach this to your hose point on your tap, and blast through with water, you'll be surpised at the amount of crud that comes out.
8 - Spray some carb cleaner into the breather box, NOT TOO MUCH though.
9 - Use a screw driver, place into the breater box and scrape as much of the gunk from the neck of the pipe as you can.
10 - Don't go too deep, about 1 1/2 inches is enough.
11 - Remove the small breater pipe and use a pin to clear the little hole that is in the centre of this pipe neck.
12 - Blast the small pipe through with carb cleaner, or thinners and water, spray in some WD40 to dry it out again.
13 - Re-assemble, replace the O rings on the inlet bridge.

It's an idea to replace the cam cover gaskets at this time, as they may have taken a punishing from the heat, but mostly from the increase in crankcase pressure.

Club Barge
3,467 Posts
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