Undiagnosed fault - red triangle, engine light, red oil warning (P0340)

Discussion in 'Gen 2 Prius Technical Discussion' started by Ant84, Jul 3, 2016.

  1. Ant84

    Ant84 New Member

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    Hi guys - new here!

    I bought a 2006 Prius here in the UK a couple of weeks ago. It's my second Prius - my last one was a total loss after covering 160,000 relatively trouble free miles so I thought I should buy another.

    However the issues have now started. A few days ago the car was driving along just fine when the red triangle appeared together with the 'problem' message followed by the red oil warning displaying in the top left corner of the screen. A few seconds later, the yellow engine light lit up and I drove the remaining mile or so back home (very slowly and carefully). I should point out that the car didn't drive any differently after these warnings appeared and I haven't noticed any strange sounds or anything like that.

    I've been out to the car on a few occasions since. It goes into ready mode just fine and drives perfectly in EV mode. The triangle and oil warning reappear shortly after the engine cuts in every time it's started. The hybrid battery charges and discharges on the display when it's left at idle as normal. A friend of mine has a cheap and cheerful diagnostic machine that he brought over and that pulled the P0340 code which relates to the camshaft position sensor. That sensor has been replaced for a brand new one and the fault codes cleared but the code is still showing.

    The next day we decided to check a couple of things to see if there was no oil pressure or a blockage somewhere simple. Oil level is fine - maybe slightly above max but not so far to cause a major issue according to my friend. The oil filter was removed and the accelerator pressed to see if any oil came out, but nothing/very little. The filter was then replaced for a new one. Then the sump was removed and the pickup checked - no blockage present. Sump put back on and we put the drained oil back into the car for now. I've also checked the voltage of the 12v battery through the in car display as detailed online - everything seems perfectly fine and the voltages are towards the higher end of the parameters, leading me to think it's a fairly new battery in good condition.

    After this we had the car trailered to a local garage and he came back saying the timing chain was stretched, the valve timing was out and the camshaft and crank weren't lining up properly. He said if this was fixed then that should solve all the issues, but I've since been told by two other mechanics that information is false and it won't fix the oil problem.

    It seems like every mechanic has a differing opinion on what is likely causing the trouble, but all of them seem reluctant to work with it. So far I've had suggested...

    - Electrical fault
    - Poor compression
    - Filled with incorrect fuel
    - Timing chain needs replacing
    - Hybrid battery faulty
    - Blockage
    - Oil relief valve

    I'm really desperate for it to be resolved but I feel like I'm banging my head against a wall and getting nowhere as nobody seems prepared to strip the engine down to find the fault. I'm hoping and praying there's nothing mechanically wrong and there's some simple electrical issue causing a false oil warning.

    I'd be really grateful for some advice on this if anyone has any ideas? Thanks.
     
  2. Ant84

    Ant84 New Member

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    Apologies.

    Could a mod please move this to the troubleshooting section if this is in the wrong subforum?
     
  3. bisco

    bisco cookie crumbler

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    welcome! how many miles on her? seems the mini vci would be the appropriate course of action for the correct codes, and toyota tech info for troubleshooting. all the best!(y)
     
  4. ChapmanF

    ChapmanF Senior Member

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    It's good that you did pull codes and try to follow them up; that's what you need to do to solve such a problem. Sadly, you learned the lesson that the little fortune-cookie code explanations that are sometimes built into scan tools or come up in google ("relates to the camshaft position sensor") are not the whole story: getting that code might not necessarily mean that the sensor is what you need to repair or replace. If you think about it, the computer that is giving you that code only knows that something isn't right with the camshaft position signal it receives, which comes from the sensor over some wires, back to the computer. The computer is trapped inside its box without eyes, instruments, or opposable thumbs, so it doesn't have any way to further pin down whether the wiring or the sensor itself are at fault (or a bad connector, or even a problem in the input circuitry within the computer itself). Figuring that out is the part of the diagnostic job that is left for the human to do.

    My best advice is to take whatever code(s) you have and look up the troubleshooting steps in the actual repair manual on techinfo.toyota.com. That doesn't give you little fortune-cookie explanations, each code will have a page number next to it where you turn for a complete troubleshooting flowchart to find out why that code came up and what you need to do about it. Following those steps might have led you to the true problem without replacing the cam sensor at all.

    -Chap
     
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, DTC P0340 points to a problem with the camshaft position sensor circuit. Since you've replaced the sensor without the code going away, more analysis needs to be done. The fault is likely in one of the following:

    Open or short in camshaft position sensor circuit
    Camshaft position sensor
    Camshaft timing pulley
    Timing chain has jumped a tooth
    ECM

    The factory repair manual explains how to test the wiring harness between the sensor and the engine ECU. If that is found to be good, then you would need to remove the engine valve cover to inspect the camshaft pulleys and the camshaft lobes. If those are found to be good, then the engine ECU would need to be replaced.
     
  6. Ant84

    Ant84 New Member

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    Thanks guys.

    The mechanic suspected a timing chain issue when he had a look over it so that makes sense.

    I figured that the problem of oil pressure has probably caused the timing chain issues though, so if we put a new timing chain on the car or reset it, won't the same problem happen again due to lack of oil pressure?
     
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    If your car is continuing to show low oil pressure, then you should probably just install a replacement used engine. The engine may have been abused by a prior owner who failed to maintain the correct oil level.

    It is possible to install an oil gauge sender on the engine, temporarily replacing the oil pressure switch located near the oil filter, so that you can see what is the oil pressure at idle speed and at 2,500 RPM. Those readings can be compared to the Toyota spec (4 psi at idle; 22-80 psi at 2,500 RPM when the engine is warmed up) to see whether the oil pressure warnings are correct or not.
     
    #7 Patrick Wong, Jul 4, 2016
    Last edited: Jul 4, 2016
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  8. Ant84

    Ant84 New Member

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    Unfortunately guys I think the Prius may be beyond worthwhile repair.

    The garage today had it up on the ramp to test oil pressure with a mechanical gauge - the needle didn't even move on the gauge at any RPM. The kid put it in drive and gave it some revs while it was up on the ramp and it seems to have made the car much worse.

    When it was lowered to the ground it was cutting out and making noises I hadn't heard before. Now the red car icon with the exclamation mark appeared and there was a strong chemical smell (sulphur) in the garage.

    If the engine, timing chain and hybrid battery need to be replaced it's just financially impossible. Pretty lousy for a car I've only had a couple of weeks!
     
  9. bisco

    bisco cookie crumbler

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    sorry to hear it, but you're probably right. cut bait, before it bleeds you to death. might be time to look for something a bit newer, with less miles. financially, a non hybrid might better fit the bill.
    all the best!(y)
     
  10. ILuvMyPriusToo

    ILuvMyPriusToo Active Member

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    Sounds like you might have a chat with the dealer who sold you the car . . . Sorry the car turned out to be a problem :(
     
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