LS430 - Need some help with some error codes

DruLS · October 6, 2019

Hi everyone,

So I'm currently on a mission to sort a few odd jobs out on my car and get it back into good health. I've been having the 'Check VSC' and CEL coming on intermittently so I've just done a scan with TechStream and here's what I currently have.

The main issues I want to solve first are the codes for the cats and O2 sensor. Now my current exhaust is not in great condition and is leaking so I'm having on having a new one made up soon. I'm hoping that a leak could cause this but I'm not sure as I'm no expert on exhausts, and I don't know if this would be related to the O2 sensor also.

Now the reason I want to sort this out first is because ECP are currently having a big sale on for the next 24 hours and I can get a really good discount on a couple of Bosch or Denso sensors. Based on these codes, would it be safe to assume that these need replacing? If so I'd like to buy the replacements right away so I can save some dosh. ECP have a 1 year return policy so I might buy them now just in case I do need them. EDIT: Just found out that these cars have 4 O2 sensors. Rock Auto lists only 3, upsteam left, upstream right and downstream. Does this mean I need two of the downstream ones? And is there any way to check which ones have gone bad because I couldn't see how to do that on TechStream.

I'm also hoping a bad O2 sensor could cause the car to think the cats aren't working properly because it's receiving bad/no info from them. The car recently went through an MOT and the emissions were fine (and this was back before it was on LPG).

C1713 just appears to be a faulty sensor so I'm not too worried about that for the time being. And it appears that C1751 and C1752 can be caused when the car is running but lifted off the ground. I've reset these and I'll see if they come back.

C1201 seems quite worrying. TechStream doesn't give much info and my research seems to indicate it could be a problem with the ECU.

Any help you guys could offer would be greatly appreciated.

The-Acre · October 7, 2019

To be honest I think doing anything with o2 sensors when you have an exhaust leak is a tad pointless as a leak could trigger a sensor code. You have two pre cat and two post cat sensors, two for each bank. If you're having a new exhaust made it really would make sense to replace them at the same time, especially if you shop around and get some good prices. Some say it's best to replace in pairs.

DruLS · October 7, 2019

3 minutes ago, The-Acre said:

To be honest I think doing anything with o2 sensors when you have an exhaust leak is a tad pointless as a leak could trigger a sensor code. You have two pre cat and two post cat sensors, two for each bank. If you're having a new exhaust made it really would make sense to replace them at the same time, especially if you shop around and get some good prices. Some say it's best to replace in pairs.

Rock Auto seem to have good prices on the OEM Denso ones. For the price I think I might just order them all and have the exhaust shop fit them while they're putting the new exhaust in. Even if they're not faulty they're known to go bad so couldn't hurt.

The-Acre · October 7, 2019

49 minutes ago, DruLS said:

Rock Auto seem to have good prices on the OEM Denso ones. For the price I think I might just order them all and have the exhaust shop fit them while they're putting the new exhaust in. Even if they're not faulty they're known to go bad so couldn't hurt.

I think that makes so much sense, it'll nice to know the whole system is sound.