Automatic Transmission issue on Vauxhall (Opel) Astra K 1.6 CDTi

chris_wheels

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Mar 25, 2023
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Make
Vauxhall (Opel)
Model
Astra
Year
2016
Miles
64000
Engine
1.6CDTi
Hello, I am trying to understand what exactly is wrong with my automatic transmission on my Astra K (2016 model, 1.6 CDTi)

Error codes:
P2723 (solenoid E performance/stuck OFF) and then a P0777 (solenoid B stuck ON). The codes come on and off.

Symptoms:
  • Trouble shifting at low gears (1st-2nd), especially when cold. I need to hold it reving around 2000rpm to force a shift. Absolutely fine at higher gears on the motorway at >30MPH
  • Problem is made worse at inclines, even small ones
  • When switching from Reverse to Drive, the engine revs for the first 3-4s before moving. When switching from Drive to Reverse though, there is no issue.
  • I have been driving it like this for weeks, at some point it improved to almost normal but now it is back to being weird.

I am just trying to understand what the exact issue is that connects all these symptoms. Obviously it is something that eventually affects transmission fluid pressure/solenoid function, but what is the route issue? From my reading I see it could be anything from low/dirty transmission fluid, to faulty wires/valves/solenoids or PCM or something breaking down.

Specific questions:

1) I took it to a transmission specialist garage, they said they have to take the gearbox out to diagnose (which is obviously costly). Is that really unavoidable or should I insist they check other things first such as transmission oil level? Do any of the above symptoms point towards a specific cause?

2) I should also add that back in November same guys changed the torque converter. Could the two issues be related in any way?


I'd be grateful for advice on any of the above - thank you.
 

billr

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I'm thinking that vehicle is not sold into the North American market, which we are focused on. However, there should be a lot of diagnosis that can be done without removing the trans. Live-data to check many sensors and operations, pressure-checks from outside the trans, and air-checks. the air-checks will require removing the pan and valve-body, but still a vastly less chore than removing the whole trans!

The fluid and filter should be fairly new, since the converter was changed recently, but it never hurts to renew those; and dropping the pan would give a chance to inspect for unusual debris in the fluid or any other obvious problem.

Yes, checking fluid level should be done before anything else!

I should note that if the shop has already done the air-checks, back when the converter was changed, they may already know that there is a problem deep inside the trans. They may be saying they need to remove the trans to fix it, not to diagnose the problem. Some of the story leading up to the converter change may give us some clues.
 

chris_wheels

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Hi Billr, thanks so much for your reply. I am indeed based in the UK. As far as I know they only ran diagnostics, they didnt mention any pressure or air-checks. I think since they recently changed the converter perhaps they assume that fluid levels etc are ok, so they suggested an issue with the solenoids themselves, or an electrical issue or a computer module issue. They said they would have to take gearbox out to check; Later they mentioned the possibility something mechanical breaking down and contaminating the fluid with metal and interfering with the solenoid electromagnetic function.

Interesting comment about them knowing something from the previous work on the converter. Although initially they said it shouldnt be too costly, last time I talked to them they were discussing the possibility of the new converter being damaged and needing re-replacement, and they also put the option on the table of selling the car if it gives me too much trouble - not sure if I am meant to read between the lines.

Regarding the previous work on torque converter, it was just giving me a P0741 error (torque converter clutch system stuck off) and at some point transmission just gave up and wouldnt shift at all. Think converter was breaking down and clogging some filter? The seller fixed it as it was within 6 months of purchase, as far as I know they replaced the converter.
 

billr

wrench
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The electrical stuff you mention, solenoids/PCM/wiring, can all be checked pretty thoroughly without removing the trans. My instinctive feeling is this is an "electrical" problem. Even that P0741... I would be surprised if the converter itself was bad; more likely something in the electricals.

See where I am heading with this? I don't have much faith in the shop you are talking to. Taking out the trans should be the last resort!

We have a member here who owns/runs a trans shop. He may not be familiar with this specific trans, but I expect can give better opinion than me. If he doesn't speak up tomorrow, as the new week starts, I will summon him.
 

chris_wheels

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Thanks a lot billr. I have very little knowledge on car issues really, but my common sense agrees with you. I did however find these guys trustworthy prior to this, they have very good reviews underscoring their honesty, didnt charge me for diagnostics, and just generally have been very friendly and taken the time to talk me through things. But as you say some things don't seem to add up. I initiated checks with them because they fixed it before, in the hopes that the new issue would be covered by their previous guarantee.

Hope your friend or others can shed more light into this - my gearbox is a 6T45 in case that helps pin down causes.
 

chris_wheels

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Just to give an update on this issue: I have been driving the car since, it hasn't got worse. and it definitely hasn't got better. A couple of weeks ago I had another transmission specialist look at it. He took it for a drive, and very quickly said the issue was that the casing (housing?) was broken and that this is a common fault in this generation of Astra K. I asked him if it could be in anyway connected to the previous issue/replacement of torque converter, he said it was not related.

He explained me all the technical details, most of which went over my head, and said it will get worse up to the point it wont move forward anymore. He quoted a price of 3K + VAT to fix it, which is a lot more than I hoped for - I bought the car for around 10K so not sure if it's worth it. Any opinion/advice would be helpful..!
 
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