406HDI accelerator not responding

craigb

Member
Fellow Frogger
Joined
Nov 26, 2011
Messages
52
Location
Adelaide
Long story but trying to condense it - went to start the car and it fired but if i put my foot on the accelerator, nothing happened. Checked under bonnet and cable was fine and turning the TPS. I then pushed and rotated the TPS from under the bonnet and it worked and i could drive the car home. (in hindsight i don't think it had anything to do with pushing it in, it was the delay in time I think). Next day car was fine but then when warm it stranded me again but this time I couldn't get it to respond and took a taxi home, got another car and then via a friend with a 406HDi wreck and grabbed the TPS off it. When i got back to the car it started fine and drove home perfectly.

Once home, went to start the car again and once again the problem was there. So changed the TPS and still didn't work, but then after say 15 sec or so, pumping the pedal started to get it reving and then behaved as normal. Turned it off and got same short delay before working. Tried the old one back again and couldn't get any response whatever i did.

I drove the car a few times with the replacement TPS and performed perfectly, just the issue to get it going. So tonight back to that friends house to his running 406HDI that started and responded perfectly and then i swapped that TPS into it and couldn't get it to work at all. Swapped the replacement one back and after delay got it to work.

Also after the problem occurred the first time there were no warnings but after the second time the engine fault light comes on and anti pollution fault message comes up. That continues to come up now every time the car starts.

Sooooo..... any ideas? My normal mechanic hasn't time to do anything tomorrow to get codes read. I should just get my own code reader... any suggestions?

Being already in the wifes eyes an ageing 2002 406 HDI 7 seater wagon, having stranded her it has signed its own exile notice. Everything works including a/c etc, 280k km, always serviced, recent battery, new windscreen and tyres and presuming this is just a sensor or something, should have many years use left - once this is fixed unfortunately after a long and happy relationship it will be for sale. Let me know if interested - located in Adelaide.
 
Update - I may have found it but will report back tomorrow. I kept googling and picked up on the suggestion of the fuel pressure sender on the fuel rail. I pulled the plug to give it a clean and it looks wet ie. diesel leaking through into the plug area. Worth a try anyway.
 
You need to check the ecu connectors you may have diesel in the ecu very common to pump into the harness and damage the contacts or ecu also check the coolant sensors


Garage C5 X7 3008 XTE
Gone but not forgotten 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
 
Thanks for reply - stupid question - is the ECU in the black box to the right of the car under the bonnet? Not picturing how diesel would get in there without a major leak? Just checked and looks dry. Will follow wires and look for any connectors elsewhere too. coolant sensor replaced relatively recently but will keep that in mind
 
The diesel or coolant or oil can easily follow the wire inside to a ecu to give you an idea a bunch of c3s needed engine bay harnesses and and fuse box’s because the washer pumps filled the fuse box from the opposite side of the engine bay


Garage C5 X7 3008 XTE
Gone but not forgotten 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
 
Oh dear! This one is nice and dry under the bonnet without diesel leaks and checked that ECU etc and all dry. Off now to get one of these fuel pressure senders off a wreck and see if it makes any difference
 
Might be worth getting the faults cleared. If it has detected a faulty TPS, the computer may have gone in to a safety mode to prevent the car taking off on its own.
 
Thanks, that's a good point - I'm swapping all these sensors but won't know if i have fixed it if the computer is still in shut down mode. An update on its behaviour - I cleaned all the connections last night and left them off to dry. This morning when i went to swap these sensors the car started and after it made its anti pollution beep, the accelerator performed fine and car went like normal. At the other end when swapping the sensors over I realised that the plug that goes into the sensor on top of the injection pump I had forgotten. Put it back on and tried to start and wouldn't work. Pulled it off and it did. I didn't have torx with me to swap that but i have now and about to go and see if that makes a difference.
 
I think I may have it but need a bit more testing to be sure and still the engine light comes on and anti pollution fault and beep, but as suggested this may require a clear codes. But it does start and instant throttle response, runs well - faultless. It didn't seem bad before apart from this no throttle, but now it appears to pull stronger, idles smoother - I guess these things change slowly and you don't realise. But yet to see if the fault warning goes.... or if it will start and work tomorrow! In the end i think it was the fuel pressure sensor that screws in from underneath the fuel rail, although the other sensor that comes off the top part of the fuel rail and clips into a plastic 'manifold', did have diesel in it and must have had some sort of leak. Who knows if that was a problem that finally reset itself. But trying to be helpful and repeated from a UK forum, that bottom one often goes.

I am going to have a go at a 700km round trip on the weekend and fingers crossed that doesn't all come unstuck! I will report back after getting codes cleared, hopefully monday. Anyway, thanks for the responses. I'm not very regular here but when i am in trouble often the answers come from here. I am a moderator on a forum and facebook for another European marque and only leaves so much time to be here, but i appreciate gratitude there when i help people and want to indicate my gratitude for the advice here. And who knows, the wife might fall back in love with the Pug this weekend but I think its days of being with us are numbered.
 
Hopefully the codes reset themselves once a fault is repaired. Apparently this is the case with 307. You have to drive it 50K's after the repair and the messages should stop.
I have just experienced this with mine after fitting a new Turbo to intercooler pipe and a new air filter. The message was Depollution System Fault and the engine light was showing. But now it's gone and the car runs very well.
I also hope your wife will give you and the car credit and forgive that something went wrong but accepts that it is possible to fix and have another time of reliability. Superstition happens with lack of understanding. That car should go for another decade at least. Our 406HDI that we still run just clocked 400,000K's and is still a great car to drive and has never let us down.
 
You need to do a number of driving cycles depending on what codes are logged


Garage C5 X7 3008 XTE
Gone but not forgotten 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
 
I agree with DMC. I have the random anti pollution on the HDI which is caused by a faulty air flow sensor takes 3 drives to ok clear, 1 drive to come back on 😂

Sent from my SM-G900I using aussiefrogs mobile app
 
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Excellent, thanks for that. I had a seal on a brake booster go a while ago and the light would come on but when driving to family on a 250km trip it would go out - so that makes sense. And as it happens heading off there in a short while so will see how it goes. I just hope i really have found the problem! - I'm sure i have!
 
Deep breaths!! Taking me a few days to compose myself.... So Saturday morning, ready for the big trip and the battery is flat - no sign of anything left on and first time this has happened. Swapped batteries and took the risk to do the 700km round trip. Car performed perfectly. Bacause battery was flat the trip computer reset and car was averaging 5.7l/100km on the open road, up to 5.8 with adelaide hills etc and back to 5.7 on flats. I didn't want to risk getting stranded so disconnected the battery overnight and started and performed perfectly next day. Sunday night just parked the car and started fine Monday morning. The engine light and anti pollution fault remained, so I took it to Mark and Lion Auto in Adelaide and he cleared the large number of codes, restarted and light gone...... all fixed right?...... then he put his foot on the accelerator and back to the original problem and no accelerator!!!

So i tried the trick of putting it in gear, foot gently off clutch until nearly stalling, while 'feathering' the throttle and it got it going. Not always first time though. I took it for 15 min drive and up to 90kmh and taking off from one light at one point there was a beep, but I wasn't quick enough to see the message if there was one. But once again, car had plenty of power, performed perfectly. Back to Mark to check codes and was just brake light switch (which has always been there.....another story) and intake air temp. Tried to restart and this time kept stalling repeatedly straight after starting. Eventually after about 10 starts it kept idling enough to do the clutch thing and got moving.

Drove the car the 25km or so home from Mark, performed faultlessly, engine light didn't come back on and even restarted after i stopped it with pedal working. Left it overnight...... battery dead flat this morning! I rang Mark and things to check he said was alternator (although it he tested that and working okay and battery load tested ok and an internal volt meter is showing 14.4 v running) - but apparently they can earth through a regulator or something and flatten overnight. I'm wondering though if the battery problem was never an issue before, is one of the sensors i put in dodgy and earthing slowly? Tonight i will pull the plugs from all the ones i changed and leave battery connected..... but then also the battery didn't go flat on Sunday night.

I can see a long road of trying to sort this, unless I give up or the wife pushes for her suggestion to take it to a wrecker. So so frustrating when it works so well once running but can't have a car that just decides to flatten its battery or decide to stop the accelerator working on its own whim.

As ever - an discussion/suggestions welcome
 
Updating that after charging battery it flattened it again on Tuesday night. Charged again - refitted, car started and worked perfectly and no engine light. Then when i parked it I disconnected all the wires to sensors that I had changed - thinking the golden rule that if you changed something and developed a problem, then rather than spreading the confusion, chances are it was something you did. But it flattened the battery again last night. I suppose one of the wires i moved could be earthing somehow, using that theory. Next thing though I am going to disconnect the wires to the alternator overnight - Mark said that sometimes a fault in a regulator can show it charging ok but then drain it overnight. Yesterday I put the battery in early afternoon and then after picking my kids up from scouts I checked a voltmeter plugged into cigarette lighter at 9.30pm, so maybe 9 hours, and it was still reading 12.3volts. This morning it was 2 volts after another 11 hours or so. Maybe I need to set an alarm and check it at times during the night and see when it starts dropping. Warm here in Adelaide and 't shirt' weather overnight.
 
I wouldn't think an alarm would help, as it'd probably be drawing current all night. A multimeter with amps will tell you, in series between the + battery lead (disconnected) and battery + terminal. But I guess that's no use anyway because it's not a solution!
 
Stuey is right you need to put a multi meter in series and check the draw then unplug everything you’ve fitted one by one looking at voltage is a waste if you don’t have a multi meter you can use a test light but a meter is better


Garage C5 X7 3008 XTE
Gone but not forgotten 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
 
I can do that, but if battery is flattening its still telling me there is a draw (isn't it?) - just where from is the issue - I guess trying to follow individual wires for current draw. I have the main engine ECU also disconnected, the other plug next to it in that black box - still draining. I guess i keep pulling things..... really sick of this car!!!
 
Yes you know you have a draw but by using the meter as soon as you disconnect the offending circuit or part you should see the draw drop to almost nothing but don’t forget the bsi needs to be asleep before you start unplugging things there are plenty of YouTube videos on this


Garage C5 X7 3008 XTE
Gone but not forgotten 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
 
I had been chasing youtube for the other problems but not the battery draining and testing - sometimes it takes someone to point out the obvious to point you in the right direction, so thanks for that. I'm not sure if the BSI was asleeep when i pulled some things some days ago -probably was though

Thinking more about your comment about the amp meter, it has to be in series, or in the line of the current doesn't it? So your last comment I take it to have it inline from the battery itself and then pull things to see if it moves. That sounds good and will try that. I guess the current draw is small enough for the tiny multi meter wires to carry that current. Otherwise my old 1960's clubman has an amp meter in the dash that has heavier wires going to it. But will try the other today.

When the car is sitting with ignition off and BSI has gone to sleep, I'm imagining there should be a very slight current draw? I don't know if the car has ever been left that long but I know my 1980's Mercedes with an aftermarket alarm will run a battery flat if left for a month or so.

Anyway, thanks again for the interest and taking your time to continue to come up with good ideas.
 
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