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Dear forum, long time reader first time poster.
i recently acquired an 07 Bentley continental GT. Car sat in a garage since 2019 so when i picked it up the battery was dead, I replaced the main battery and had the starter battery tested which tested okay so I left that one. After I replaced the battery I got an engine light “fan 1 circuit low” I did some digging and found that a fuse was blown. Replaced the fuse and fan is blowing again. Car has 39k miles and runs consistently around 200 degrees in the dash gauge. Runs and drives great. Well a few hours after the battery change I got another warning, ran the code with an OBD II and the new code was “knock sensor low circuit”
I have done a lot of research and found that these are pretty inexpensive sensors but it’s possible the entire engine needs to come out to replace them.
im fairly versed and experienced in Benz and Range Rover repairs but this is my first W12. I’ve read that it is possible to change them with the intake manifold removed but quite difficult. If it’s possible then im up for the challenge but if this isn’t even a remote possibility I’d rather not attempt it.
before I start pulling my hair out, could this sensor read out be due to the battery being replaced and the electronics coming on board and going a bit haywire?
and if it is a knock sensor is it indeed possible to replace these without removing the motor?
worst case scenario I need to take it in does anyone have a rough idea what the cost involved would run roughly?
this forum has been a bible for loads of other topics so any help/suggestions would be greatly appreciated
Quote: "before I start pulling my hair out, could this sensor read out be due to the battery being replaced and the electronics coming on board and going a bit haywire"?
As you said above, usually a dormant Bentley will throw spurious codes. Sometimes other functions don't work properly until a few drive cycles when various modules wake up. Clear the codes individually than drive and re-scan. The knock sensor isn't a common problem on these cars, although? 😏
Hopefully you are using more than a generic OBD scanner. Most here use RossTech VCDS.
Thank you so much for the reply @1eapplebaum I greatly appreciate it and I’ll continue to put some miles on it. The brakes were completely shot so I haven’t really been able to drive it more than around the block a few times. I’ve got new brakes and rotors plus my RossTech interface arriving next week, I just ordered these yesterday. I’ll put my panic on hold
As to your issues, let's see what the actual fault code is for the knock sensors when you receive the Ross-Tech, this will pin point which sensor, as there are 4 of them.
Being that you haven't driven it far, have you replaced or topped off the 2019 fuel in the tank ?
Do you have any sign of rodents, possibly a chewed wire.
As to the knock sensors being replaced by removing the intake manifold, I would venture to say, no, as the knock sensors are not under the intake manifold, nor anywhere near it, they are on the block (2 each side) down below each cylinder head, meaning mounted to the block below each exhaust manifold, and depending on the side, each is buried by certain accessories and or turbos, the drivers side (LHD) has the turbo and the AC compressor in the way, same for the passenger side as far as turbo and some piping, I am not saying totally impossible without dropping the engine assembly, BUT it is definitely worth a look from the bottom up for access, not from the intake manifold down.
Johnny
. Driver's side LHD Driver's side LHD Driver's side LHD Just to show how buried there are. Driver's side LHD Passenger's side LHD DS LHD
Thank you @Johnny Hotspur GT you are a LEGEND.
There are luckily no signs of any rodent infestation in or around the motor, nothing chewed and no droppings where it was parked.
as for the fuel, the quarter tank it had was siphoned out and new fuel filled up.
I’ll save my panic for after I get the RossTech but knowing there is an alight possibility of accessing those sensors from underneath does bring some comfort.
Thank you for the pics, these are beyond helpful to have even if I don’t have to tackle those sensors.
