Matching You with a Pre-Screened Smog Check Center You will Love
Free Online Smog Check Diagnosis
$500 Free Consumer Repair Assistance
Failed Emissions Test
How to Pass the Test
Who Else Wants To Pass the Smog Check
Miles: 
Which Type Should I Choose?
 
            
    Forum > Failed Smog Test > Question

Join the community and post your questions. Ask-A-Tech right now!
 
 



Failed Smog Test
 

Toyota Sienna failed smog for PO125 PO135 and PO155

My 1999 Toyota sienna failed Smog Test. With a trouble code machine I got codes PO125 &PO135 & PO155.

I replaced A/F sensor B1-1(denzo) and B2-1 and o2 heated downstream sensor and CTF all brand new. I replaced the termostat as well. Why am I still getting the same trouble codes after 3-4 miles? Please help me. Thank you.




Answer:  

You've replaced several emission sensors with no change in Check Engine Light results. Often simply replacing a trouble component does not mean the system has been repaired. In this particular case we recommend making sure each sensor is communicating with the ECU properly, and reference voltage & ground is available at each sensor (as required).

When more than three components are indicated to be failing we often notice a ground problem or ECU reference voltage problem.

The following are general trouble code descriptions:

OBD II DTC P0125 - Insufficient Coolant Temperature For Closed Loop Fuel Control

Engine coolant temperature (ECT) sensor indicating engine has not reached closed-loop operation required temperature within 160 seconds. Possible faults may include faulty ECT sensor, defective ECT wiring or harness, low engine coolant levels, stuck open thermostat.


OBD II Trouble Code DTC P0135 - Oxygen O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)

Possible faults include high O2 Heater element resistance, high wiring and/or harness resistance, open or short in the O2 Heater Ground circuit.


Since you've already replaced both bank 1 and bank 2 sensors, we highly recommend checking the ground source.


OBD II Trouble Code DTC P0155 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

(same as P0135 except for Bank 2)


posted by SmogTips Support 09-05-2012 01:55 PM


Related questions and answers you might find useful:

2000 Mercedes Benz slk230 Kompressor, I took it to get a Star Smog. I disconnected the battery So Now The Computter Will Not Reset On This Vehicle. I have Tookin It To 3 Smog Shops And Have been charged. but no help. by Sara on 10-21-2017 12:55 AM

Will a p0401 "egr insufficient flow" code cause my 2004 f350 6.0 powerstroke to fail a california smog check even if there is no check engine light? by Eric on 10-20-2017 02:28 PM

2001 Oldsmobile Alero Dashboard Lights On Sometimes by jr on 10-16-2017 12:01 PM

What Are The Reasons My Nissan Altima Has High NOx? by Albert on 10-13-2017 03:48 PM

OBD Trouble Code P0741 Torque Converter Clutch Circuit Problem by al on 10-08-2017 03:09 PM