01 V70 Cold Weather Engine Codes

[tappolon]

Just bought a used 01 V70 T5 wagon (with the third row seat) as a replacement for the old 97 850 wagon that never worked reliably. Bought this one from a mechanic who likes working on volvos and took the 850 off our hands also as partial trade. Well, now that the temperature has dropped here in MN just 2 weeks later the engine is running rough and cutting out while driving. I pulled the codes and spoke with the mechanic. He had the same issue last winter but thought he had solved it by swapping the engine and replacing all sensors, but now he thinks that it was the warmer weather that solved the issue since it wasn't a problem at all since last winter. He's willing to spend some time digging into it and let me drive a 99 wagon he has in the meantime. He thinks it must be wiring related at this point because of all the other things he did. If he can't figure this one out I may end up with a different vehicle that doesn't have the third row seat, which although not required is a huge value for me with our big family. Checking for input to help get to the bottom of this. Thanks!

Here are the codes that came up:
P0422 - Main Catalyst Efficiency Below Threshold (Bank 1)
P0455 - Evaporative Emission System Leak Detected (Gross Leak/No Flow)
P0237 - Turbocharger/Supercharger Boost Sensor A Circuit Low
P0236 - Turbocharger/Supercharger Boost Sensor A Circuit Range/Performance
P0102 - Mass Or Volume Air Flow A Circuit Low Input
P0453 - Evaporative Emission System Pressure Sensor/Switch High Input

[chrism]

Wow! Those errors run the gamut and it’s difficult to construct a correlation between all of them. I would be inclined to unlatch the ECM, clean all the contacts, and reinstall it. It takes a special lock/unlock tool to do it properly. Other than the cost of the tool it costs nothing to try, and it eliminates a, somewhat common, point of failure that can affect many different things.

[tappolon]

He said something about that but said he hasn't taken one off before. What's the tool?

[chrism]

ECM Removal Tool:

https://www.amazon.com/CTA-Tools-1070-R ... moval+tool

Also, from the Haynes manual for P2 Volvos, here is a drawing with dimensions to make your own tool.

download/file.php?id=35721

[mrbrian200]

Wow! Those errors run the gamut and it’s difficult to construct a correlation between all of them. I would be inclined to unlatch the ECM, clean all the contacts, and reinstall it. It takes a special lock/unlock tool to do it properly. Other than the cost of the tool it costs nothing to try, and it eliminates a, somewhat common, point of failure that can affect many different things.

There might be a correlation, a major EVAP system leak or stuck EVAP solenoid valve would throw off the AFR and potentially trigger DTCs for the engine management sensors (MAF, Boost, O2). If AFR is all out of whack the ECU might interpret as a problem with those sensors and/or the catalyst in addition to catching that the EVAP system/tank isn't holding pressure.

[abscate]

Stop
Clear codes
See what comes back first.

A once had a loose charge air hose that drove about 8 codes over time

[JRL]

Also you need to stop pulling generic codes and get it on VIDA.
The codes are more specific

Frankly you need a GOOD Volvo tech to look at it, they're more familiar with weird 01-02 multiple issues like this.
Your mechanic may be "OK" but you need someone who does these for a living every day.

[mrbrian200]

A once had a loose charge air hose that drove about 8 codes over time

One relatively simple issue can trigger a cascade of DTCs because the ECU doesn't actually try to diagnose the actual problem. It merely stores a list of abnormal sensor readings.