Help Needed with diagnosis of emission failure and cont'd ODB code P0125, fail to closed loop.
Hi There,
I hoping to find someone who may have experienced the same type of problem or someone knowledgeable in the witchcraft of emissions interpetation/Lexus codes. I and a number of people I have consulted have come up empty with solutions apart from replacing the entire fuel system / emission system / catalytic system.
1998 gs 400 emission failed due to ASM2525 HC ppm limit 52/180 value, idle limit 150/230 value, CO% limit ASM2525 limit 0.29/4.30 value, idle CO% limit 0.70/4.01 value. NOx ppm passed.
ODB codes history
First set of codes were PO125 temp for closed loop, P0150 B2S1 circuit malfucntion, P0153 B2S1 circuit slow, P0171 system lean, P0150 B2S1, P0153 B2S1.
Reset ECM, replaced B2S1 O2 sensor (original Denso with Delphi OEM 4 wire LTW.7595, 0938T1 coding on sensor), replaced cooling system thermostat WITH OEM.
Emission failed again with codes again PO125 temp for closed loop, P0150 B2S1 circuit malfunction, P0153 B2S1 circuit slow ONLY. HC and O2 values consistent with first result. Reset ECM, road test until CEL and checked code, only one P0125.
This is first emission fail for a routinely maintained GS 400. Mileage is high but was also on previous 2 year emission pass with flying colours. Your expert advise would be greatly appreciated as only other thoughts are CAT replacement/injectors etc which would be costly mistake to make. HELP!!
Trim Values at idle
Ignition advance - 11.0 deg
Injector Pulse Width - 2.69 msec
Long Term FT Bank 1 - 8.59%
Long Term FT Bank 2 - 15.62%
Mass Air Flow 4.7 g/s
O2 Sensor 1/2 Volts - 0.61 V
O2 Sensor 2/1 Volts - 0.00 V
Short Term FT Bank 1 - -0.78%
Short Term FT Bank 2 - 19.53%
Total FT Bank 1 - 1.00
Total FT Bank 2 - 1.00
DTCS - 2
Ignition Advance 12.0 deg
Long Term FT Bank 1 - 8.59%
Long Term FT Bank 2 - 15.62%
Mass Air Flow 4.4 g/s
O2 Sensor 1/2 Volts - 0.50 Volts
O2 Sensor 2/1 Volts - 0.00 Volts
O2 Sensor 2/2 Volts - 0.87 Volts
O2S B1S1 Lean/Rich 0.00 msec
O2S B1S1 Lean/Rich 0.00 msec
O2S B2S1 Lean/Rich 0.00 msec
More info
Engine Speed 736 RPM
Coolant Temp 203 degF
O2 Sensor 1/1 Volts 0.67 Volts
Vehicle Speed Sensor 0 mph
Calc Engine Load 14%
DTCS 2
Ignition Advance 12.0 deg
Long Term FT Bank 1 8.59%
Long Term FT Bank 2 15.62%
Mass Air Flow 4.2 g/s
O2 Sensor 1/2 Volts - 0.19 Volts
O2 Sensor 2/1 Volts - 0.00 Volts
Please help! Apart from beginning the replacment of components without true justification that they are faulty, I intend to check wiring harnesses carefully and ECM. Thanks!!