2002 volvo v70 turbo boost pressure sensor 9125462

[RickHaleParker]

The first time we got codes it said PO 236, and PO 237.

P0237 (P zero 237) Format is PXXXX where XXXX are numbers.

Wiring or sensor.

• Contact resistance in the terminals
  Short-circuit to supply voltage in the signal cable
  Open-circuit in the signal cable
  Defective boost pressure sensor.

P0236 is done at start up. The boost pressure sensor is compared to the atmospheric pressure sensor. If they different P0236 is set. When the turbo is not engaged both sensors are exposed to atmospheric pressure.

[petervee]

Yea. let's see when I replace the booster.

[petervee]

I believe so...we'll see when I get it....

[RickHaleParker]

You're probably OK. It looks like the only one used on the AME 2002 V70 is Volvo Part number 8677288. That year, the North America V70s did not get the newer versions of the engines. They where all version 3, none with versions 4 & 5.

[petervee]

Yes. That is the one I ordered.

[precopster]

I've yet to find an atmo sensor on any Volvo turbo engine post 2000. In any case there is no monitoring of atmo pressure in Vida for these models. My 2006 XC90 2.5T has the same code and has had a new Genuine BPS fitted. Code is still there.....knowing Murphy's Law it was too easy to swap out the sensor and that's why it didn't fix the problem.

Volvo faults regarding incorrect boost can be attributed to a leaky TCV (turbo control valve)
Also if you read with Vida/Dice, the exact nature of the code is revealed such as "signal too low", "signal too high" or "incorrect signal"

Air leaks around the throttle/intercooler pipe and swapping the turbo control valve are my next targets. Fuel consumption around town on ours is at 22.5L/100 now (usually 16-18)

Highway mileage on a 2002 2.4T should be much better than 28mpg. My 2001 V70T5 gets bw 32 and 35mpg easily with a new Mac valve TCV or BCS as it's sometimes known as.

[abscate]

This one place where using a code-to-part replace strategy will cost you parts dart money

[petervee]

Thanks

[RickHaleParker]

I've yet to find an atmo sensor on any Volvo turbo engine post 2000.

If memory serves me correctly that function was moved to the MAF. Air density can be calculated from Mass Flow and Temperature. A MAF sensor can measure both.

[EngineeringBloke]

The MAF sensor has a temperature sensor. It is the electronic component (thermister - temperature sensitive resister) that is a small cylinder with wires that run to it and back from the part of the MAF with the contacts. The air flow is measured by a hot film plate (about the size of your small finger nail) that is recessed into a channel underneath the thermister.

As more air flows it cools the plate which is heated to restore it to its operating temperature. If the air is cold, then an adjustment is made.

So the MAF is able to provide Intake Air Temperature and intake air mass. If there are no leaks after this, then the air mass will be corrected, even if the turbo is adding boost pressure (as more air will be 'pulled' in past the MAF).

The Boost sensor or MAP will measure the air pressure after the turbo and intercooler to be used by the ECM.