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Mike, UK Car Mechanic
Category: UK Car
Satisfied Customers: 39198
Experience:  Hi, I am a Car/ vehicle technician of 34 years. 29of -running my own repair/diagnostic business.
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I have a 04 plate Toyota Avensis which has starting problems

Customer Question

I have a 04 plate Toyota Avensis which has starting problems when the engine is hot. The vehicle starts from cold each time and will start when hot if you try immediately after switching the engine off. Leave for five/ten minutes and the vehicle will not start. When driving the vehicle shows no problems and runs as normal. The engine cranks over when hot and the battery shows no signs of wear. The vehicle charges the battery as normal. Initially the fault was intermittant and most times the vehicle would start. The fault has now become worse and the vehicle will not start when hot. Leave the vehicle for a couple of hours and the engine will start as it will start when left overnight. The fuel pressure has been checked and when hot falls to about 22 bar. When running the pressure is about 34 bar. The management systems show that no fault is stored and nothing is therefore apparantly wrong. may this indicate a mechanical failure? Toyota garage suggested the starter motor. Can you help?
Submitted: 8 years ago.
Category: UK Car
Expert:  Mike replied 8 years ago.
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Mike :

Hello and Welcome to justanswer...

From what you have described this sounds like an Ect sensor problem... This is the engine coolant sensor - not the one the controls the gauge - but the one that sends signals to the cars Ecu.. main computer - re. the temperature of the engine.

The Ecu then sends commands to the fueling and ignition systems according. If the sensor is faulty and thus sends incorrect , or no info to the ecu as above, the fuel and air mixture will be incorrect and thus do as you describe resulting in poor running and no start situations...

If you remember the old auto and manual choke works like that , only electronically. If and when the choke was in the wrong position for the temp of the engine, the engine either wouldn't start or coughed and spluttered... exactly the same.

Even diagnostic checks don't always show this sensor up as faulty and in fact - more often often than not, they don't... So its well worth renewing that sensor. Its usually located on the inlet thermostat housing , inlet manifold or thereabouts depending on model and has a two wires pin connector going to it.

Always buy one from a dealer / genuine unit. If you are unsure as to its position - ask the parts dept; when you are in there, to show you on the screen where it is located ....

Fit that and all should be well again ;)

I Sincerely XXXXX XXXXX have helped you - Please ask me if you need more help...

Kind Rgds, MIKE

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The problem is in the starter motor not sending the correct signal to the crankshaft sensor when the engine is hot. the motor binds up and the signal is reduced or non existant and therefore the remedy is to replace the complete starter motor. I had the local toyota technician inform me that the motor was to blame but with no explanation as to what the cause was. Bosch suggested to me that it could be the crankshaft sensor as their systems operate efficiantly at the pressures given in the question. I then contacted the toyota technical department who explained the tie up with the starter motor and crankshaft sensor and everything then fell into place. Please feel free to use this advice to any other avensis customer you may have in the future with the same problem.