Trouble codes MAF / O2 1st bank?

ANDREWCHI

MEMBER
2008 TOYOTA CAMRY
4 CYL
2WD
AUTOMATIC
135,000 MILES

Problem: 2008 Toyota Camry LE
Failure Code P0171
I changed MAF sensor and the 02 sensor
New DENSO 234-9049 02 sensor and DENSO MAF 197-6110 sensor
Checked for vacuum leaks
Now that the two sensors are changed out I have a new code P2237.
I drive the car about 30 miles the check engine light is off. When I turn off the engine and then start the car again after 5 minutes the check engine light comes on with this new code P2237.
I tried two more times clearing the code and re starting it after a drive. I get the same results each time.

If I put the old DENSO 234-9049 02 sensor back I get the check engine light and P0171 code again and the system sets up with 6 registers ready.
If I put the new DENSO 234-9049 02 sensor in again I get the check engine light P2237 code
with 3 registers ready.
I have checked the fuses and the relays they are all good.

Where do I go from here?

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

It sounds like the new oxygen sensor is the wrong one or is defective. I would get another one.

P0171 - System Too Lean (Bank 1)
P2237 - Oxygen (A/F) Sensor Pumping Current Circuit/Open (Bank 1, Sensor 1)

Can I ask if the engine has an exhaust leak? This will cause a lean code. Here is a guide to help you check for vacuum leaks, test with the engine cold only.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please go over this guide as well:

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

Please upload pictures or videos in your response of any problems so we can see what to help you with.