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Error code: P0171 System too lean A/F lean malfunction bank 1


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Dear all

I would be very grateful for any advice. I would particularly like to hear from anyone who has had a similar problem and has solved it. My mechanic thinks that it is an automatic gearbox problem.

This is a January 2008 2400cc hybrid petrol Alphard, which I have had for about 10 months.

The problem started a month ago immediately after repairs to the rear suspension. The problem comes and goes and is most marked at higher speeds and when climbing. The engine ‘jerks’ under acceleration, misses beats and has reduced power (50 mph on motorway climbing).

The error code: ‘P0171 System too lean A/F lean malfunction bank 1’ has come up twice. This states that the engine is running with a reduced fuel mixture, but my mechanic has looked at this twice and is convinced that this is just a symptom of a deeper problem.

Actions taken so far: coil and plugs changed, gearbox oil changed and all pipework checked for air leaks.

Any suggestions?

My mechanic thinks that it is an automatic gearbox problem and that it will be expensive…

Best wishes

Ian

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To me this sounds like a fuel problem as you say when the symptoms happen the engine is under load, acceleration, motorway etc. I am going to refer to my Octavia which had a loss of power, this was caused by a partially blocked fuel filter.................Just a thought

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P0171 is front lamba sensor or maf sensor not gearbox it's a fuel air ratio problem I would personally change maf sensor first as I have had  same problem with my 3.0 also chuck in a bottle of cat cleaner in the fuel and give it a good blast on the motorway I have been adding cat cleaner now once a month and not had any problems since .

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Fantastic! I really appreciate the opportunity to get experienced advice on this forum.

I will ask Alex (my mechanic) to do these things.

Very best wishes

Ian

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  • 4 weeks later...

Can I give an update on the Toyota Alphard?

We replaced the MAF sensor (£160).

All seemed well.

I went to Halfords last Saturday and put catalytic cleaner into a 1/8th full tank. I drove 15 mins (as suggested) then stopped to fill up with V-Power unleaded petrol (mechanic said this would clean the engine).

I drove on. 5 minutes later the engine cut-out. I had to have the car recovered (£200!) as it would not start.

Since then it has been at home. If I start it, it runs normally for a few seconds or longer, then cuts out. Once it ran for two minutes. The engine sounds normal. I wondered if it is the computer which is cutting the engine because it is getting some sort of 'serious error' code?

A few thoughts:

  • Is the catalytic cleaner in the fuel line a problem, which will clear
  • Can these cars use V-Power fuel?
  • Any other suggestions?

Regards

Ian

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1 hour ago, Ian S said:

Can I give an update on the Toyota Alphard?

We replaced the MAF sensor (£160).

All seemed well.

I went to Halfords last Saturday and put catalytic cleaner into a 1/8th full tank. I drove 15 mins (as suggested) then stopped to fill up with V-Power unleaded petrol (mechanic said this would clean the engine).

I drove on. 5 minutes later the engine cut-out. I had to have the car recovered (£200!) as it would not start.

Since then it has been at home. If I start it, it runs normally for a few seconds or longer, then cuts out. Once it ran for two minutes. The engine sounds normal. I wondered if it is the computer which is cutting the engine because it is getting some sort of 'serious error' code?

A few thoughts:

  • Is the catalytic cleaner in the fuel line a problem, which will clear
  • Can these cars use V-Power fuel?
  • Any other suggestions?

Regards

Ian

, E

Hi Ian

 

Sorry to hear about your issues.

 

Fuelling your van with Shell V Power (E5) should be fine. It's probably ethanol free !

I don't use it, but feel you will receive reassurance from members that do use it

Is this the first time you have used the Shell fuel ?

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Yes. It was just a suggestion from the mechanic that if I was using catalytic cleaner then using the 'super' unleaded might also be a good idea as it contains cleaning agents.

I usually use the 'ordinary'

Any other thoughts?

Do I need a Toyota main dealer??

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3 hours ago, Ian S said:

Yes. It was just a suggestion from the mechanic that if I was using catalytic cleaner then using the 'super' unleaded might also be a good idea as it contains cleaning agents.

I usually use the 'ordinary'

Any other thoughts?

Do I need a Toyota main dealer??

 

Hi, Ian,

 

Honestly, I don't know what you need !

Finding a Toyota dealer to work on a grey import is no easy task !

 

I have full confidence in any advice that Picasso gives, otherwise I would not have called upon him for an opinion.

 

I am not a mechanic but I fail to understand why your mechanic thought you convertors needed a clean.

 

How many miles has your machine done ?

 

I'll send you a PM of the dealer that I bought my Alphie from.

I believe, there is a garage 'next door' that does his work; not far from you.

 

Perhaps a phone call to them may be helpful.

 

I expect Picasso will be back on this thread asap.

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On the 2.4 you have 2 lamba sensors what a lot of people don't know is the 1st one bank one is a fuel ratio sensor and rear one bank 2 is a oxygen sensor I still, believe you have a fuel ratio sensor fault which is why your alphard not running right it not getting the correct fuel and air mix .

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The engine computer light is glowing. My mechanic is sending someone on Monday to read the codes at our house to see if we can find the issue and avoid another recovery to the garage.

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Ignition coil pack you have 4 bank 1 is 1st coil pack in the line I would replace all 4 and whilst there change the spark plugs to iridium plugs if you want part no. Please give your vin number 

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