Check engine light

No code tells you to replace a part , need to do diagnostic's for said code .
P0141 - O2 Heater Circuit (Bank 1, Sensor 2) Description: See the description for DTC P0135. Possible Causes: See the possible causes for DTC P0135. Diagnostic Aids: See the diagnostic aids for DTC P0135. Application Key On Engine Off Key On Engine Running Continuous Memory All GO to Pinpoint Test DW .
DW: Heated Oxygen Sensor (HO2S) DW: Introduction DW1 CHECK FOR DIAGNOSTIC TROUBLE CODES (DTCS) Are DTCs P0040, P0041, P0053, P0054, P0055, P0059, P0060, P0132, P0133, P0135, P0138, P0139, P0141, P0144, P0147, P0152, P0153, P0155, P0158, P0159, P0161, or P1127 present?
Yes No For DTCs P0040 or P0041, GO to DW2 .

For DTCs P0053, P0054, P0055, P0059 or P0060, GO to DW14 .

For DTCs P0132, P0138, P0144, P0152 or P0158, GO to DW20 .

For DTCs P0133 or P0153, GO to DW3 .

For DTCs P0135, P0139, P0141, P0147, P0155, P0159 or P0161, GO to DW9 .

For DTC P1127, GO to DW19 . For all others, GO to Section 4, Diagnostic Trouble Code (DTC) Charts and Descriptions .
DW9 DTCS P0135, P0139, P0141, P0147, P0155, P0159 OR P0161: CHECK FOR A SOURCE OF POTENTIAL HO2S CONTAMINATION

• Investigate the following items as potential sources of HO2S contamination:
  • use of unapproved silicon sealers
  • fuel contaminated by silicon additives
  • excessive oil consumption
  • glycol leaking internally in the engine
  • lead-contaminated fuel
  • short drive cycles in cold weather
  • use of unapproved cleaning agents

Is a concern present?
Yes No REPAIR the source of the contamination.

CHANGE the engine oil and oil filter.

RESET the keep alive memory (KAM). REFER to Section 2, Resetting The Keep Alive Memory (KAM) .

REPEAT the self-test. GO to DW10 .

Probably replaced a good sensor. This codes could be from a bad sensor, a vacuum leak, or an exhaust leak before the sensor.

P0138 O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
P0139 O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)
P0325 Knock Sensor 1 Circuit (Bank 1 or Single Sensor) -Circuit Malfunction
think you just need a new o2 sensor

P0138 O2 Sensor Circuit High Voltage
P0139 O2 Sensor Circuit Slow Response
P0420 Catalyst System Efficiency Below Threshold

First things to check and clean is the MAF sensor and the IAC valve...these two cause problems from carbon and dirt buildup...use MAF cleaner only....if this works, great, if not....

Clean trottle body....or

Check for a plugged catalytic converter...remove the O2 sensors and start the car, does it seem better? If it does change the catalyst..

Hi, guys. you can read this article first. Why check engine light is on. Maybe it is able to help you. Good luck.

Trouble codes are normaly 4 digits with a "P" or "B" before it. I am gonna assume that you meant P0138 and P0401:
P0138 is Oxygen Sensor Circuit High Voltage (Bank 1, Sensor 2)
P0401 is Exhaust Gas Recirculation Flow Insufficient Detected

A code P0138 may mean that one or more of the following has happened:

• Faulty O2 sensor
• Short to battery voltage in O2 sensor signal circuit
• High fuel pressure (not as likely)

Possible Solutions Here are some potential solutions:

• Replace O2 sensor
• Repair short to battery voltage in o2 sensor signal circuit

for info on the P0401:
http://www.obd-codes.com/p0401

P0138 - Oxygen Sensor Circuit High Voltage (Bank1, Sensor2)

P0139 - Oxygen Sensor Circuit Slow Response (Bank1, Sensor2)

The Heated Oxygen Sensor (1 or 2) located rear of catalytic converter produces an output signal relative to oxygen storage capacity of catalytic converter. Ho2S 2 signal is less active than signal produced by front oxygen sensor. This code sets when HO2 Sensor voltage is greater than 999 mV for more than 2 minutes (time depends on model. Could be as high as 4 minutes)

Symptoms: There may be no noticeable symptoms except for MIL illumination. Possible high fuel pressure can over rich the system.

Causes: A code P0138 may mean that one or more of the following has happened:
* Faulty O2 sensor
* Short to battery voltage in O2 sensor signal circuit
* High fuel pressure (not as likely)

Here are some potential solutions:
* Replace O2 sensor
* Repair short to battery voltage in o2 sensor signal circuit

Hope helps (remember to rate this answer).

Possible mass airflow sensor. A cheaper way to get around paying for the super expensive 2001 Path part is to use the same year maxima sensor since they use the same motor :)

Hi Garcha,

Both codes relate to O2 Sensor # 2

Code P0139: O2 Sensor Circuit Slow Response - Bank 1, Sensor 2
Code P0140: O2 Sensor Circuit No Activity Detected - Bank 1, Sensor 2

A faulty O2 sensor will mean incorrect signals will be sent to the EFI computer, causing erratic engine running.


Cheers,


"If this has helped you in any way, please rate this solution" :-)

You said you changed the O2 sensors, which ones? I do believe that sensor 2 is the Catalyst efficiency monitor, it looks like an O2 but it's function is different. This sensor is behind the Catalytic converter, the O2 is in front. Bank one is the bank that # 1 cylinder is on, so the sensor that is defective is the 2nd sensor back on that sides exhaust pipe.

P0141 - Heated Oxygen Sensor (HO2S) Heater Performance Bank 1 Sensor 2

P0138 - Heated Oxygen Sensor (HO2S) Circuit High Voltage Bank 1 Sensor 2