Check Engine - P0157

[crager34]

Got this code yesterday and did a search and read all the topics. I only seen one that said replace the O2 sensor and many that talked about cleaning/replacing the MAF sensor.

Best advice - Do one, both...????

O2 sensor is $75 and I don't even know where Bank 2 Sensor 2 is.

Thanks

[johnnyapollo]

Sometimes you'll get that code if there's corrosion on the MAF - I'd try cleaning first - make sure you get MAF-safe cleaner (it'll tell you on the can).

-- John

[twistedsymphony]

the code is for low voltage on the after cat O2 sensor...

On other cars this typically means it's a busted sensor...

search around for a reasonably priced direct replacement. I had one go on another car of mine... OEM sensor was $130 but I found a direct replacement Bosch sensor for $25 new... looked identical to the one I took off the car too.

If the after cat sensor died it could be signs of a failing cat...

What I would do: first clean the plug... unplug it spray both sides of the connector with contact cleaner (found at radio shack or other electronic stores) and plug and unplug the sensor a few times, if that doesn't work, replace the sensor.

there's no harm in cleaning your MAF (or cleaning anything for that matter)... typically if the maf is dirty you'll have a rough idle too...

I suppose if the maf was dirty it would throw off the map and cause the engine to run out of spec resulting in low sensor readings...

[crager34]

Good advice and will begin the cleaning this week. I just replaced the PCV valve (again and I do often) and the check engine light magically dissappeared.

[Hotsauce]

You can also get this as a false code if EGR gasket is bad, EGR nut loose, or manifold gasket blown(common)

It comes from admitting unmetered air into the engine, more than the fuel trims can handle.

John C.

[Rednex]

Guys,

I've got mentioned symptoms - "check engine" on, engine roughing on idle;
Can you point me where 2 look for mentioned sensor (MAF) & PCV valve?

Thanx a bunch,
E.

[don moore]

I got the same code ..same issue..o2 sensor... did a bottle of HEET and it went away..its the gas in my area ..thats cloging up alot of sensors around here ..I got a check engine light on the wifes PT Cruiser ...same issue...around the same time ..from a cheap gas station...

[crager34]

This doesn't have anything to do with the HHO install does it?

Nope. I got some MAF Sensor cleaner from Checker and code is gone. However, I will probably replace the O2 sensors at some point, for maintenance. She isn't getting any younger ya know.

[alanbradley]

Aha! I know this one...

It happens on mine when the air being taken into the engine is in excess of 60C. This happens when the engine is warm (after a long run or heavy use) and when you come to rest the residual heat in the engine bay warms the air in the intake system. Whether this code shows or not is also dependent on the weather - sticky, humid weather seems to make the code more likely to register.

One of the first times this happened to me was when I'd driven into a long, narrow car park with a large trailer behind me and then had to reverse back up the car park, turn around and reverse back down. All of the shunting in reverse and straightening up was hard work and there was no airflow through the engine bay.

Its very much an "intermittent" code and can be cleared as soon as the pocket of hot air has passed through the intake system. The temperature just seems to confuse the ecu somewhat...

Hope that helps,

Alan