OBD Codes

gasgas

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I'm very gradually getting interested in doing my own fault finding of car computers. There's less knuckle banging than changing wheel bearings. Specifically my granddaughter's VW Polo sometimes has the engine management light on, which would obviously fail the MOT. I want to sell it, as I have already had to buy her a newer car.
Some time ago I bought an OBDII analyser, just a £35 one but even so not the cheapest and I have sometimes just pressed the 'clear the fault' button on this and other vehicles. This makes the offending light go out, but like a bad penny it comes back later.
Today I pluggedthe tester in and actually read the owners manual that came with it and found it had a P0106 fault code but all the list of tests it did seem to be OK to me -but what do I know? Not a lot, of course. Of the 21 things it read, all were OK or N/A except
Load PCT 36.5,
Load ECT34,
SHRT FT1 -2.3%,
MAP (kPa) 47,
RPM 1363,
Vss 6Km/h
I am guessing, but looking at Google my best guess sounds as if MAP means Manifold Pressure, and looking at google it would seem that the manifold pressure might be wrong. I've no idea if 47kPa is high or low, or what it should be. I suppose I should now look up what manifold pressure at 1363rpm should be.
In fact a few months ago when this issue first appeared I paid a garage to do an analysis and all he said was that one of the three cylinders was low on compression. I guess that the manifold tested would be the inlet manifold, and this google article says there is a sensor there which should be producing 1v to 4.5v. I wonder if wiring in an AA cell or two would convince the car that it is OK?
Any thoughts? I suppose if the compression is low on one cylinder it would reduce the vacuum in the inlet manifold, that's all I can think of. Meanwhile I am quite impressed with this little OBDII tester, it was £35 I seem to remember.
What is really annoying is that although the car drives quite well, it would fail the MOT just because the inlet manifold pressure is a bit low. How on earth does that make the car unfit to be on the road? Similarly apparently other things that can cause the EML to come on include the petrol filler flap not closed properly, even if the actual cap is screwed on tight. It's all very annoying. Next they'll start failing a car because the paint has faded.
If you want to read the google, here it is:
@trevskoda what do you reckon I should be looking at, short of searching Google Maps for a scrap yard? I think I'll spray some AMS cleaning fluid down its throat.
 
Orange light comes on in my car every 400 miles or so then goes out at same again, h book says car wont run on e10 fuel, so maybe the problem
My mates in a garage where i worked can turn it off before the mot so not bothered.
A ggod cure is to cut the signal wire behind the dash and cross connect the battery light, so after starting its of, sneeky but works.
I have tried the cleaning flueds but just a wast of dosh.
 
Stick a bit of black tape covering the engine management light on dash.
 
Stick a bit of black tape covering the engine management light on dash.
the light needs to be seen to come on and then go off, so that is not a solution.

(if the vehicle was registered before a certain date, the EML is not part of an MOT test and so would not be an MOT fail anyway (that bit does rely on the tester knowing the handbook ;) ))
 
It's not like The Olden Days when if your oil pressure light stayed on you could just remove the bulb!
Keen to learn I have found an excellent video explaining how the MAF and MAP sensors work, what they do, what the engine does if they go faulty, and what multimeter readings they should give if working properly:
A ggod cure is to cut the signal wire behind the dash and cross connect the battery light, so after starting its of, sneeky but works.
I was told by my MOT tester that they turn on the ignition - all the lights should come on for two seconds - start the engine and they should all go off. So I don't think you can actually mess with the lights / wiring, unless you have a fat brown envelope to give to the tester. Which I think must have happened with this car I am trying to fix. I bought it with a year's MOT. The tracking was so far out that one front wheel scrubbed itself through all the steel bands and popped, and the handbrake cable had snapped and rusted through several years ago by the look of it.
Anyway I am very excited to find that I can discover lots of things about these new fangled car computerised things on youtube. Tomorrow I will be ripping out the MAF and MAP sensors and measuring them. I would rather spend £59 on a new sensor than have another garage tell me it's something else that costs £950 as has happened in the past, when the actual fault was a cheap sensor. At two separate garages on two separate faults.
 
Here’s a very interesting video. I have a peugeot boxer that had this problem solved now thanks to this video . This guy is very clever.

 
Here’s a very interesting video. I have a peugeot boxer that had this problem solved now thanks to this video . This guy is very clever.

Is this the External Temperature Monitor Failed/Missing Fault, Wully?

Steve
 
Steve the van I bought the sensor was missing and the engine management light would come on van wouldn’t give full power and the air conditioning wouldn’t work it set off about 8 different faults £80 for a mirror from eBay now it’s fine.
 
Orange light comes on in my car every 400 miles or so then goes out at same again, h book says car wont run on e10 fuel, so maybe the problem
My mates in a garage where i worked can turn it off before the mot so not bothered.
A ggod cure is to cut the signal wire behind the dash and cross connect the battery light, so after starting its of, sneeky but works.
I have tried the cleaning flueds but just a wast of dosh.
I refuse to put E10 in our cars cos it's POO Fuel I only use Super Unleaded 97 or 99 octane.
 
I didn't know an engine light was a failure, I just googled to find:-


If the light remains on once the engine is started, it is classed as a major fault under the new MOT rules. This does not apply to petrol vehicles registered before 1 July 2003 and diesel vehicles registered before 1 July 2008. There are many different reasons why the engine light might be on.
 
Hooray and woopee doo! I've fixed it and I am a very happy bunny because a) this is the first time I have fixed the electronics on a modern car and b) because I will not be going back to the garage that charged me £60 to tell me the car needs a new engine and c) all fault codes have gone. Having viewed that video I removed the Mass Air Flow sensor and it was filthy dirty, all covered in crud. I cleaned it with brake cleaner / electrical cleaner and got rid of all the crud. Refitted the sensor, erased the stored codes and went for a 4 mile drive. No engine warning light.
This will add about £450 to the value of the car because I can now get a new MOT and someone said they will pay £950 for it with a years MOT. I was offering it to advertisement responders for £500 and had no takers. Apologies for the pictures, the first is out of focus but you can see the crud, and the second is what it looked like after cleaning,
1693216606602.jpeg
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