The engine now runs ok when started cold, but if the weather is very hot or it's started when warm it goes into limp mode, whereby the orange spanner symbol comes on and max acceleration is only 1/3 it should be.

I thought it was caused by oil deposits by putting in 2 stroke oil by mistake, but this is looking less likely (see discussion below).

I needed to empty a fuel can which I thought was petrol only, but after adding say 200ml to a full tank of fuel I realized it was a 20:1 2 stroke oil mix.

So far I've tried:

  • EGR cleaner spray into the air inlet & cleaning EGR with brake cleaner, fine carbon layer no oil.

  • Spark plugs had oil deposits but actual arc surface was ok, put new plugs in.

  • Used a bottle of redex injector cleaner at recommended mix in 2 full tanks.

ECU codes:

  • P0400 Exhaust Gas Recirculation (EGR) Valve Range/Performance (Closed Valve)

  • P1122 Acceleration Pedals Position Sensor 2 Voltage Low

  • P1550 ELectronic Throttle Limp Home, LImited Performance

  • P1120 Acceleration Pedal Position Sensor 1-2 Correlation

  • P0136 O2 Sensor Circuit Voltage High

  • P1405 Exhaust Gas Recirculation (EGR) Sensor Circuit Low

  • Year is 2001, Engine is 1.6L SFI (Z16SE)

I'm guessing some of these might be red herrings or interconnected, which one(s) to target first? The guy who did the codes said the Limp mode was caused by the exhaust blowing by the flexible joint (which it does slightly) but it blew much worse in the past & didn't cause limp mode so I wasn't convinced by that particular theory.

Any suggestions on what to look at would be most appreciated.

  • Welcome to the site. What year is the Astra?
    – Zaid
    Commented Aug 18, 2016 at 20:58
  • Try running injector cleaner at higher than recommended concentration? Commented Aug 18, 2016 at 21:20
  • thanks both, Year 2000, mmm, good idea about high concentration, I wonder what strength I can get away with without reducing calorific value to the point the engine stalls. Commented Aug 18, 2016 at 22:31
  • 1
    Maybe change the subject of the question to "What causes 'limp mode' in Vauxhall cars?" I suspect that's the question that needs to be answered, and by chaining the title you'd be more likely to attract folks who know.
    – dlu
    Commented Aug 19, 2016 at 0:51
  • 1
    You should take your car down to your local auto shop and get the ecu error codes scanned then post them here (or buy a cheap scanner and do it yourself).
    – Jason C
    Commented Aug 19, 2016 at 6:48

3 Answers 3


Essentially you have put 10 milliliters of oil in your gastank

I have done this before with more oil than that on accident into my truck.

My solution was to fill the tank to the top and dilute it as much as possible. This worked fine for me and I had no ill effects that I am aware of. The truck passed emissions after that and I have had no maintenance issues.

If you are still concerned you can always drain your fuel tank. Many Vauxhall's have a drain plug in the fuel tank. If yours does not you can always siphon out the majority of the gas and then fill it up with fresh fuel.

Once you have diluted the oil down to an acceptable level you should not have any more issues.

  • sadly I already tried the max dilution approach & it didn't work, probably I should have drained the tank at that point, but I thought the problem would go away after a tank or two, but it didn't... So I think there are residual oil deposits somewhere which are causing slight misfire which the computer is responding to with the limp mode. Commented Aug 18, 2016 at 22:33
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    That's doubtful in my mind. The gasoline would wash the residual away. The issues you have can be unrelated to the oil. Commented Aug 18, 2016 at 23:02

I'm having trouble seeing the "oil event" and the "limp mode" as being related. When you added the oil, it was – as @DucatiKiller pointed out – only about 10 ml. This went into about 48 liters of fuel. First, it would take a long time for that amount of oil to even run through the engine, so I think it would be highly unlikely that you'd notice a problem until you'd consumed most of the tank of fuel – if you were going to see a problem from the oil at all. Second, I don't think there are any sensors upstream of the engine that would be affected by the oil, and downstream this amount of oil pales in comparison to cars that are "oil burners" – the ones you see going down the highway with a cloud of smoke. That oil would be affecting downstream sensors even if it wasn't running through the combustion chamber.

So I think the blame for the ECU putting the engine into limp mode lies elsewhere.

  • Ah... I assumed the two things were linked because they happened at the same time, but maybe not. The Engine codes are Commented Aug 19, 2016 at 7:55
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    Added ECU codes to main question above for readability Commented Aug 19, 2016 at 17:32

The problem most likely is from your engine ecu, when engine warms up the thin wires from inside electronic control unit they dilated and break the electrical connection... these ecu-s have a common issue..take a look on my repair https://www.youtube.com/watch?v=ELh5d7fKj3E

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