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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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Hi.I have a .Toyota Hi Ace 2002 model year,with a D4D engine.Have

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Hi. I have a .Toyota Hi Ace 2002 model year,with a D4D engine.Have got a diagnostic code,P0190.Was advised to change the fuel rail with sensors. Have done that,but the problem is still there. Think the problem must be in the electric circuit. Can you please advice me. Best regards XXXXX XXXXX Norway.

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Customer: replied 4 years ago.


I have checked the Connectors on the fuel pump and on the fuel rail.

Then the DTC code P0190 went away,but a New came up-P0100.Which tells the airmetering Device near the air filter dont work properly.It was locked on one figure-not working.(but the engine started)

As a last trial I disconnected the Connector on the fuel pump-the one nearest to the engine Block.Then the engine started working properly,and the DTC`s was good-0 errors!

Dont know how long it will work-will try to go for a test drive tomorrow.

Will let you know how it works out.

Best regards XXXXX XXXXX Øvretveit

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Hello and Welcome to justanswer..

My name isXXXXX have been asked to help you with this issue.

The fault code you had - the P0190 - the Toyota definition for that fault code - and what needs to be done is as follows:

Fault code - P0190 Toyota D4D.

The Fuel Rail Pressure (FRP) sensor is a diaphragm strain gauge device in which resistance changes with pressure.

The electrical resistance of a strain gauge increases as pressure increases, and the resistance decreases as the pressure decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signal to the Powertrain Control Module (PCM - or Ecu ) corresponding to pressure.

Strain gauge type sensors are consider passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow.

Voltage that is dropped across a fixed resistor in series with the sensor resistor determines the voltage signal at the PCM / Ecu.

This voltage signal is equal to the reference voltage less the voltage drop across the fixed resistor.

The FRP sensor measures the pressure of the fuel near the fuel injectors. This signal is used by the PCM to adjust the fuel injector pulse width and meter fuel to each combustion cylinder.

Symptoms with the fault code P0190:

- Engine Light ON (or Service Engine Soon Warning Light) - Engine will not start


- High fuel pressure - Low fuel pressure - Damaged FRP sensor - Excessive resistance in the circuit - Low or no fuel - Wiring harness connector of the fuel pressure sensor - Fuel Rail Pressure Sensor - Fuel..

So the above need to be checked with regard to that fault / code on this model.

As for the P0100 code - P0100 Mass or Volume Air Flow Circuit Malfunction... This is the air flow meter / circuit as you mention.

This when faulty - or its circuit , can and will also cause non start symptoms - but please note, thats its correct function can be governed by loose fittings / air piping - split / perished piping - bad / faulty;loose connections to the meter etc - so all this needs to be checked before condemning the meter itself.

Too - the meter sensor inside the grills may be dirty - you can use a spray cleaner for this through the grills - but you should never strip the meter / touch the sensor as this will usually damage it.

Also - carefully check the air filter system is not in need of renewal / cleaning first...

Working through as above should help you get this issue sorted for you ..

Please bear in mind too that if all checks out as ok then the fuel system - filter and pump -pressures etc inc injectors would then need to be checked / investigated with suitable test equipment - best usually at a diesel specialist for that if it should come to that.

Let me know if you need anything more on this at all -

Meantime -- Please click on the OK rating to Excellent ratings service for me now, Thank you for that... and you can get back to me anytime if you need / wish..

Best Rgds, MIKE.

Please note, you are rating the content of my "answer" - my help to you - not the "system" which can experience delays etc which are not under my personal control -or delays caused by "time -off" which we all have on occasion - Thank you.

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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