P0446 and B1442 codes on a new (old) 2008

Hello!

My partner and I are moving back to the US and recently purchased a 2008 Prius for her to drive to and from work.

The last few times she's driven it, the check engine light has been on. She's in the US on her own at the moment - I'm due to travel over later this month. I'm hoping someone might be able to offer some wisdom on how much to be worried / what to do about it (I've been trying to diagnose it remotely via a blurry WhatsApp call).

Last week, I sent her an OBDII reader and had her read the codes. It came up with "P0446", which I've read might be due to a loose gap cap. The gas cap was re-tightened to make sure it clicked, but the code has come back.

This week, I sent her an Autel MaxiAP200 reader, that I've read on this forum provides more detail.

For the engine/emissions, it gave

• P0446: Evap system vent control circuit. $7E8. Current.
• P0446: Evap system vent control circuit. $7E8. Pending.

It also had some codes for the AC:

• B1421: Solar sensor circuit (passenger side). Current.
• B1442: Air inlet damper control servomotor. History.

She also generated a report for the P0446 code (I guess this shows what was happening when the code was generating?):


*****
DTC that caused required freeze frame data storage: P0446

Parameters:
- Calculated load value: 87.5%
- Engine coolant temperature: 77°C
- Engine RPM: 2713 rpm
- Vehicle speed: 57 km/h
- Intake air temperature: 25°C
- Absolute throttle position: 31.8%
- Time since engine start: 197 sec
- Number of warm-ups since DTCs cleared: 3
- Distance traveled since DTCs cleared: 27 km
- Control module voltage: 13.769 V
- Ambient air temperature: 23°C
- Engine run time since DTCs cleared: 0 hrs, 58 min

Fuel System:
- Fuel system A status: CL
- Fuel system B status: --
- Short term fuel trim - bank 1: -0.8%
- Long term fuel trim - bank 1: 2.3%
- Commanded evaporative purge: 0.0%
- Fuel/air commanded equivalence ratio: 0.993

Engine:
- Ignition timing advance for #1 cylinder: 22.0°
- Air flow rate from mass air flow sensor: 23.37 g/s
- Barometric pressure: 99 kPa
- Absolute load value: 58.0%

Oxygen Sensors:
- Oxygen sensor output voltage bank 1-sensor 2: 0.680 V
- Short term fuel trim bank 1-sensor 2: 99.2%
- Equivalence ratio (lambda)(bank 1-sensor 1): 0.995
- Oxygen sensor voltage (bank 1-sensor 1): 3.318 V

EVAP System:
- EVAP system vapor pressure: -48.25 Pa
- Absolute EVAP system vapour pressure: 100.095 kPa

Catalyst Temperatures:
- Bank 1, sensor 1: 653.3°C
- Bank 1, sensor 2: 427.3°C

Throttle:
- Relative throttle position: 16.1%
- Absolute throttle position B: 69.8%
- Commanded throttle actuator control: 31.8%
*****

I've ordered a new gas cap and will have her fit that when it arrives (the old gas cap looks pretty worn - see attached image). I'm not sure if the above report suggests that will fix the problem, or if there is some other issue with the Evap system?

Also, should I be worried about the B1442 code? I've read it is to do with switching between outside / recirculating air? I haven't had a chance to check the air filter. (I think I've read that the B1421 is nothing to worry about?)

Thank you in advance! She's a nervous driver as is, and the check engine light isn't helping, so any help/advice is greatly appreciated!

 

She replaced the gas cap and cleared the codes, but the CEL has just come back on (same codes again).

 

Thank you, that's extremely helpful! Seems like something I should leave up to a mechanic then. I'll have my partner tell them that they might want to start by looking at the pressure switching valve!

 

I forgot to ask - if it is indeed the pressure switching valve, does anyone have any idea how much the part + labour usually costs? I'd like to mentally prepare myself if it is going to be a big number

 

Just to follow up on this for anyone else who might have the same code. It was indeed the pressure switching valve. It came to around $250 with parts and labor (if I remember correctly).

Thanks to everyone who helped out! Now just to get it to the bodyshop after a deer collision last week...