I Need Help Fixing P-0125 and P-1155 1999 Camry Detected Trouble Codes

Question

Hello - I have a 1999 Camry V6 that has been sitting idle for about 2 years. It has 102K miles. I recently replaced the battery, changed the oil and took it for inspection. It passed. However, upon leaving the inspection station, the check engine light came on. Great timing, huh?

I hooked my OB2 tool to it and noted 2 trouble codes - P-0125 and P-1155. Assuming that the downstream mixture sensor was the culprit (the same thing happened to my 2002 Camry V6), I bought and installed the proper DENSO sensor (between the cat converter and the muffler). As it turns out, this did not fix the problem. The car runs fine after I manually clear the codes, but they will both return within 15 minutes running time. As an added irritating 'bonus', both the ABS and TRAC lights will also come on, but will extinguish if the car is restarted.

Any clues as to what might be happening? I really doubt that this is a thermostat problem as the coolant temperature is at least 199 degrees when the check engine light comes on. At idle after a 15 minute drive, my tool reports that the bank 1, sensor 1 voltage readings are .66 volts, .78% LEAN, the bank 1, sensor 2 reading is .77 volts, and the bank 2, sensor 1 reading is .66 volts. I believe that the ABS problems might stem from a loose connection as the failure can sometimes be reproduced by revving the engine. I'll fix this later

Thanks - in advance for any help.

Joe Burch

Answer 1

P0125 Insufficient coolant temperature for closed loop operation

P1155 A / F sensor heater circuit Malfunction Bank 2 Sensor 1

These code are for the upstream A/F sensor Bank 2 sensor 1 or what is commonly reffered to as a 02 sensor. Sensor 1 are the upstream 02 sensor right before the catalytic. P0125 does not mean it is a thermostat issue but the 02 sensor (P1155) is unable to perfrom feedback to correct air to fuel ratio. As for the voltage reading a .56 volts would be considered normal.  At idle if the 02 reports 0.66 to 0.76 this would be considered normal. Perfroma a MAF cleaning see if that helps. As for the CK ENG LT, whenever the CK ENG LT comes on, the vehicle is no longer operating at manufactuer specification, so for safety the ABS and TRAC are disabled.