My Car: Volvo S40 2002 1.9T.

My Issue: Check Engine Light On (for almost 2 yrs. now, for about 6-8 months the light used to come on & off, but over the last 1.5 yrs. or so, the Check Engine Light is permanently on.

Problems: The car momentarily does not respond to acceleration or picks up speed as in with a sticky transmission (both this happens rarely and has not been a major issue).

Major issue is: Not clearing Emissions!

Diagnosis: Asked a mobile mechanic (NOT a Volvo expert). He read following OBD Codes:
P0237
P0171
P0131

And, he said car needs a Turbo Charger, and that he would charge $250 to install.

My Questions:
a) Is the diagnosis correct?
b) If so, how much should I expect to spend on this repair?

I appreciate any help/guidance from learned readers.

 

P0237 - turbo boost sensor A circuit low
P0171 - system too lean
P0131 - O2 sensor circuit voltage low (bank 1, sensor 1)

I would not replace the turbo.

I would start with the O2 sensor, to take care of p0131. This can cause p0171 but I would also check for air leaks post MAF and maybe clean the MAF as these will also cause p0171.

I couldn't find much info on p0237 (did a very quick search just to see what it was) but i assume checking the sensor and replacing it if necessary would clear that up.

My state doesn't do emissions anymore but if i remember right, having more than 1 or 2 CEL codes is an automatic fail.

Good luck.

 

Appreciate your feedback!

 

p0237 could be a cracked vacuum line or the boost sensor or its connector. I'd check/fix the vacuum lines/intake air leaks from the turbo to the MAF, clear codes and see if any codes resets. My sense says all three are related to air leaks or vacuum line problems. Not uncommon for an air leak to trigger an O2 sensor code.

 

The boost code could also be a bad https://www.ipdusa.com/products/7625...ntrol-solenoid . You might want to get a boost gauge on it to make sure.

 

Thanks for the feedback, will try & get back if the fixes worked!

 

Firstly many thanks to those who responded with suggestions!
I got the car checked by a Volvo mechanic (not the regular Volvo dealer). He said he would charge $47 (fixed rate however long it takes) to let me know what's wrong.
He said the Booster Sensor was most likely the issue as there was some pressure loss. He said, we will rplc. the Booster Sensor first and see if error codes go away; if it did not then we need to further tests.
Fortunately, that was all it needed. Spent $225 (labor + part) totally. He waived the $47 diagnostic fee. Car also runs smoother.