I hope someone might know what this may be. I have a 2003 206 1.6 hatch with automatic transmission. The speedo at time drops down to zero only to come back to the normal speed after a few seconds or a few minutes. When this happens there is a drop in engine power - say 15%. I would like to have it corrected as it is an annoyance. Thanks.
Speedo Intermittently Incorrect
- Thread starter John505
- Start date
I say if power is falling away, speed sensor, speed sensor gear, or associated wiring.
Someone else may have a more definitive idea.
I will do the error code read that you suggest. Thanks.
Do you get any associated lights on the dash?
Does your car have ABS? If so, I would expect an ABS light with this fault. If not, the speed sensor is located above the differential housing on the back of the AL4 gearbox.
Bosch ME7.4.4 uses car speed in engine management calculations. So a drop in power would not surprise me.
If your car does not have ABS, the speed sensor supplies data to the engine ECU and the engine ECU puts that data on the CAN BUS. I.E. to the speedo. I don't think this fault (speed sensor) brings on an engine light (but not sure). It will log a fault code though.
If you do have ABS, the ABS ECU generates the speed data and puts that data on the CAN BUS for the engine ECU, speedo ETC to use. Again, ABS fault should bring on the ABS light.
It is a petrol car. The ABS does not send a warning light at the time the speedo malfunctions. Nor is there any check engine light. I have yet to connect my scan tool and see if there are any logged errors.
John505
Oh wait on - the car does not have ABS. I was getting mixed up with my other car - a Mi16.
I connected the OBD scan tool (Foxwell) and I cannot find any codes. So I am not sure where that leaves me.
John505
In that case it will have a speed sensor on the back of the AL4.
I have seen this fault before on a CitroenC3 and it was NOT the speed sensor.
It's still possible that the speed sensor is at fault but no use going off half cocked.
I will have to do some research and get back to you.
I have seen this fault before on a CitroenC3 and it was NOT the speed sensor.
It's still possible that the speed sensor is at fault but no use going off half cocked.
I will have to do some research and get back to you.
Ok I found the post and it was the speed sensor. Initially the new sensor didn't work but it needed the code cleared before it would work. It had stopped working completely though.
That was on a TU3 (1.4) engine probably with a Sagem S2PM ECU.
Because it's an intermittent fault it might be logged as "pending". Or it might be a code the scanner cant read? Dunno.
If you can back probe the speed sensor connector, pin 1 is "12V", pin 2 is ground and pin 3 is pulses when the wheels are turning.
I think you can remove the speed sensor and turn the input shaft with a screwdriver to simulate the wheels turning?
Of course you can only try this when the speedo isn't working. When the speedo is working it's pointless testing anything.
That was on a TU3 (1.4) engine probably with a Sagem S2PM ECU.
Because it's an intermittent fault it might be logged as "pending". Or it might be a code the scanner cant read? Dunno.
If you can back probe the speed sensor connector, pin 1 is "12V", pin 2 is ground and pin 3 is pulses when the wheels are turning.
I think you can remove the speed sensor and turn the input shaft with a screwdriver to simulate the wheels turning?
Of course you can only try this when the speedo isn't working. When the speedo is working it's pointless testing anything.
Mine is a 1.6 twin cam motor (TU5) with a Bosch ECU. The "pending" code on the scanner did not reveal any fault codes. I suppose I could try your "back probe" method and see what I get. But I would have to wait until the fault occurred again. Interesting. Thanks John505