I have a 2001 Toyota Sienna CE with engine codes P1135 and P1155. I am looking for a way to bypass the oxygen sensors, as well as suggestions regarding the lack of engine power.
As long as it is slowly accelerated, it can do OK. But if accelerated too quickly, it bogs down. And when it goes up a bridge, it will slow down by
10-15 mph.From the information that I've found on the web, the codes should not cause the engine to run as it does. This is because the oxygen sensor heater circuits will not influence the car computer - it is merely an open heater circuit. The purpose of the oxygen heater circuit is to heat up the oxygen sensor when the engine is first turned on to warm it for accurate cold running operation and input to the vehicle computer. Once the engine is at operating temperature, it is basically useless.
The main issue is this:
When the car is put in drive, it seems to bog down if given too much acceleration (gas) at one time so an easy, steady touch as you accelerate is needed to gain speed. It could take one mile to get to 40mph sadly. Going up bridges is terrible because it seems to choke up and struggle and drops 10-15 mph in speed. Once up to 40-50mph on flat road, it runs good, can get to 60mph if work at it. If you take off slowly and gradually increase speed, it seems to run fine just so slow to accelerate with power.
The codes indicate an issue with the oxygen sensor heater circuit but online discussion consensus would indicate that the heater circuit should not influence engine management and the running of the engine.
I took the van to Aamco and was told that it is definitely not the transmission.
On Toyoto Sienna's prior to 2001 there was a serviceable fuel filter external to the fuel tank. From 2001 on, the filter is in the fuel tank. I do not have a pressure gauge to measure the fuel pressure out of the fuel pump so I do not know if the filter in the fuel tank is clogged.
There are 3 catalytic converters on this van with a V6 engine.
The codes do not specifically indicate an oxygen sensor failure, only an oxygen heater circuit failure. I do not know if there would be another specific code for a failed oxygen sensor or if the oxygen heater circuit failure is a catch-all for any oxygen sensor problem.
I have found online oxygen simulators that can be spliced into the oxygen sensor wiring to simulate the proper operation of the oxygen sensor and preclude the reporting of the sensor error code.
Thanks, Adam