Who Knows Fault Codes?

[sls]

Previa model 2001 2ltr petrol & Rav model 2002 2ltr petrol both have same symptons. After long runs MIL lamp comes on, same fault codes on both vehicles suggests all four lambda sensors. come on that can not be right, but fitted all four to the Previa (at great cost) still the same. both vehicles have about 48K on the clocks, both run & perform fine. MIL stays off untill 2 or 3 hundred mile run.

any thoughts would be massively appreciated.

regards Steve

[mr-g]

Previa model 2001 2ltr petrol & Rav model 2002 2ltr petrol both have same symptons. After long runs MIL lamp comes on, same fault codes on both vehicles suggests all four lambda sensors. come on that can not be right, but fitted all four to the Previa (at great cost) still the same. both vehicles have about 48K on the clocks, both run & perform fine. MIL stays off untill 2 or 3 hundred mile run.

any thoughts would be massively appreciated.

regards Steve

Both of these models suffer from the same problem. "Catalytic system below threshold (B!, S1/ B2, S1etc.)"

The engine ECU is comparing the pre-cat oxygen sensor output with that of the post-cat sensor. In both of these cases there are 2 pre-cat and two post cat sensors.These are referred to as Bank 1 Sensors 1 & 2, Bank 2 Sensors 1 & 2. The cats are integral with the exhaust manifold. Bank 1 refers to the cat that exhaust gas from cylinder 1 flows through and you will observe that this is at the flywheel end of the engine. If you take the manifold heat shield off this will become apparent. Sensor 1 is a pre-cat oxygen sensor (also referred to as an A/F sensor). Sensor 2 is a post cat sensor. Within the mapping of the engine ECU the parameter of the comparison between sensors 1 & 2 is too fine. A calibration upgrade is available for both these vehicles depending on the calibration ID of the existing ECUs. If the upgrades have been applied and the fault remains, the next step is replacement of the manivertor. Quite often the oxygen sensors get seized in the manivertors. I don't know if the upgrades are available outside the Toyota network.