LPG Discussion Forum

Typical, During the holidays my car stops switching to LPG and 00515 - Camshaft Position (Hall) Sensor (G40): No Signal , with my car hooked up to VCDS on my my VW Golf.

I suspect my Prins VSI conversion is taking it's engine speed data from it thus won't switch to LPG and it looks like a total whore to replace. Full on cambelt removal, which requires removal of the utter bastard of an engine mounting block to loosen the valve timing pulley enough to swap out the sensor.

I don't have access to any prins diagnostic equipment unfortunately, Anybody got any bright ideas how I can reliably check the wiring isn't at fault first, ( one pin of the plug is at 1v, middle one is 0.9v (probably the signal wire) and the other is ground, but it seems to stay like that when connected and the engine is running ) or confirm the fault code?

Assuming its working on petrol then the hall sensor must be working, have you done some miles on petrol alone to see if it throws up the fault code again ?? If its fine on petrol then maybe its a poor connection or lpg fuse or something.

Yes. I would also look for the bleeding obvious before starting a full tear down to change a component that looks to be operational on petrol. If it is operational on petrol obviously.

If the signal is week its enough probably to stop the system from running,but as said above check for the obviouse first,coolant level etc.

Its also possible that an RPM filter might have been used[depending on the installer] these are flakey to say the least,they have also been unnecessary for the last 4 years or so,how old is the install??

hth woody

Many petrol management systems are smart enough to run with busted cam sensor, if a crank sensor is also fitted. It's just a case of trying to start using alternate crank pulses as a guide, and if that doesn't fire try the other crank pulses.

I should say at the time it stopped switching to gas, it also now runs unpredictably on petrol, the engine ether is sluggish or surging, but it runs. The Engine has a crankshaft sensor to work with too. My understanding is the crankshaft sensor is the one that if faulty will stop the engine running. Thats the easy one to change too.

Coolant levels look as usual, I look under the hood most weeks, no apparent leaks. The heater works well too and the vaporiser takes water from those lines fairly close to the cabin with enough wiggle room to work on the pipes, so I'd be shocked if that was a problem. but I suppose when I go out later, it won't hurt to check if the vaporiser is nice and warm when the engine is.

200 miles in a couple of days and absolutely drinking the petrol too. I'm a bit too chicken to play with the cam belt for obvious reasons.

Ignore the gas system for the time being. If it isn't right on petrol it never will be on LPG. Get it running right on petrol and chances are the LPG system will sort itself out.

Gilbertd wrote:Ignore the gas system for the time being. If it isn't right on petrol it never will be on LPG. Get it running right on petrol and chances are the LPG system will sort itself out.

I suspect your right. I'm guessing the only way to reliably check the wiring is to find what pins on the ECU correspond to the sensor connect to the sensor and check for continuity.

Continuity checks won't show up magnetic issues - weak magnet, excess gap, debris

The cables to the cam/crank sensor if they are the hall effect type should have 3 wires:

5 volts
Gnd
Signal

On my bmw the cables for both my cam/crank sensors are as above, however the signal wire is also almost a 5 volts, I think its about 4.8 but when its near a tooth it gets pulled down to near GND, I found that when mine went fault the cables in the plug were shorting together due to insulation breakdown, if u do by a new sensor dont go for a cheap option get proper VW parts. I paid 95 quid for a new crank position sensor.

Mark.

beamerguy wrote:The cables to the cam/crank sensor if they are the hall effect type should have 3 wires:

5 volts
Gnd
Signal

On my bmw the cables for both my cam/crank sensors are as above, however the signal wire is also almost a 5 volts, I think its about 4.8 but when its near a tooth it gets pulled down to near GND, I found that when mine went fault the cables in the plug were shorting together due to insulation breakdown, if u do by a new sensor dont go for a cheap option get proper VW parts. I paid 95 quid for a new crank position sensor.

Mark.

I guessed that much, about the pins . My voltages look off so I'd best look for leakage between wires.

Edit: Rechecked the Wiring.

I couldn't fine any shorts between the wires except on crazy high resistance scales. even then only 1000K or 1Mega Omhs scales.

The 5v and ground wires are good, signal wire is floating at 4.7v on average, the sensor is not pulling that voltage down at all like it should. I check an identical looking sensor and wires on a mates Seat. it's the same except when the engine is running the signal voltage is does get pulled down around 1V.

The local garage has a new sensor on order my will sort that out and fit a new cam and aux belts in the morning.

I found that with some of the cheaper hall effect sensors that they desolder them selfs inside due to the low melting point of the solder and the heat from the engine and thus creating an open circuit inside. I dare say that when you fit the new sensor all should be well again.

Mark.

New sensor fixed it a goodin. shame it took all morning. back and running on gas.

however I'm clearly not very lucky. my clutch went on my mile long trip home, the clutch master cylinder by the sound of it.

All you can say to that is YAY ! And BOO, HISS at the same time. Unlucky. Don't waste a quid on a lottery ticket this week