When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
"CHECK ENGINE" and "VSC OFF" comes on above about 3500 RPM. Camshaft sensors faulty?
Hi everyone, I own a 1998 LS400, and just got it back from the shop after some maintenance work (distributor belt, water pump and thermostat housing which was leaking).
On the motorway, while accelerating, the little red light on the dashboard started blinking, and the errors "CHECK ENGINE" and "VSC OFF" were displayed. At lower RPM, the "CHECK ENGINE" disappeared again, but "VSC OFF" remained.
I pulled over at a gas station, took the keys out of the ignition, then back in, started the car and continued the drive.
The "check engine" error did not come back until I passed 3500 RPM again to test this, however the "VSC OFF" seemed to come on randomly now, even at lower RPM.
I went back to the workshop, they read out the error codes and it said a cam shaft sensor is faulty.
I will have these sensors replaced, but I'm a bit worried about the "VSC off". Has anyone experienced something similar? And why would the error for the cam sensors only pop up after this maintenance work?
The engine runs smoothly, so the sync of cam & crankshaft seems to be fine, according to the workshop.
EDIT: The error code is P0340.
P.S. Not sure how relevant this is, but the shop also had trouble reading out the error memory, and used settings on their device for newer LS models. They are a small workshop, not a Lexus dealership.
Last edited by blacklexus1998; 10-14-23 at 06:10 AM.
VSC off is automatically turned off if there are fault codes (or for most of them) so ignore it. Do you have the exact code? If a cam sensor code then yes the shop messed up something. Damaged sensor or damaged connector is most likely.
VSC off is automatically turned off if there are fault codes (or for most of them) so ignore it. Do you have the exact code? If a cam sensor code then yes the shop messed up something. Damaged sensor or damaged connector is most likely.
Thank you for your reply. I sadly do not have the code - my bad - but I will call the shop on monday morning to ask about it. How likely is it, that the shop damaged the sensors or the wiring?
Q: The "distributor belt" is the timing belt, yes?
You probably didn't have to change all the camshaft related sensors. But hopefully, changing all sensors will fix the CEL. A lot of people (myself included) mistakenly use "cam position sensor" for for both the VVT and cam position interchangeably.
The trouble code should point to the offending sensor. There are separate trouble codes for the cam and VVT sensors. I'm thinking it's the camshaft position sensor that's under the timing belt cover that's setting the trouble code (P0340). The wire harness for this sensor can get strained when removing the cover to access the timing belt. The VVT sensors (located in each cylinder head) and their wire harness should not need to be disturbed when doing the timing belt change.
The check engine light coming on at 3500RPM is probably due to one of the sensors not seeing the camshaft position retard when VVTi activates.
I figured out the code, P0340, so the cam position sensor should be the culprit. I don't have a workshop at my disposal, I rent a garage in the inner city and lighting/space is very bad. It would be very tough for me to inspect it myself. I'm thinking of handing it back to the shop. How likely is it, that the shop damaged it? I'm thinking it's pretty likely since the error wasn't there before.
It is an often case that a skipped timing or a stretched timing belt also causes this problem.
That sounds bad, really bad. It would be unsafe to drive. I haven't driven since then, the shop didn't have time for me yet. Next week I got an appointment with them and I'm planning to drive over there and leave it there until they fix it. Is there any way to check the timing belt tension myself, without taking parts out of the car?
Can you also tell me how the 1998 1UZ-FE belt tensioner works? I can't find much about it, but I am thinking from the diagrams I found that it's a hydraulic tensioner.
10-13-23, 07:31 AM
"CHECK ENGINE" and "VSC OFF" comes on above about 3500 RPM. Camshaft sensors faulty?
