P1153 & P1157 with poor MPG

Hi all I have recently replaced my thermostat and throttle body and all is working fine. However, I do not have any lights but when I connected it to my cheapo obd2 scanner, it came up with these codes. They are:

P1153 - it says look at manufacturers manual - a google search says its a heated 02 sensor??

P1157 - same as above but not sure what it is

P1161 - not sure what it is

P0122 - TPS sensor circuit??

Car drives fine but do have ridiculously low mpg of 22-25

Hi

Clear the codes with the OBD tool (all those that will) the drive the car again.

Reconnect OBD reader and list the new or remaining codes.

Cleared the codes and scanned again. No fault codes found. But can this change after a bit of driving?

Have you owned the car from new?

When you first turn the the ignition on, does the engine light come on, then go out?

Those O2 codes should bring the engine light on.

Remove the upstream and downstream O2 sensors and swap them around. The connectors are different colours but they will still plug in. The sensors are exactly the same only the length of the wiring and the colour of the plugs are different. Remember green to blue, blue to green.

I think there is a problem with the upstream (pre-cat) O2 sensor (the green sensor).

If the codes change it's the O2 sensor. If they don't, its the connectors or wiring.

If your scanner can do it, look at the long term fuel trims, they are probably off the chart. I believe the upstream O2 sensor is giving a false lean condition and the engine ECU is trying to compensate by adding more fuel. Hence the poor MPG performance.

As far as the TPS (throttle position sensor) goes, unplug the electrical connector at the throttle body and look for moisture/corrosion. Inspect the wiring between the throttle body and the engine ECU. Unplug the the 3 engine ECU plugs and inspect for moisture/corrosion. Do this first as corrosion in the engine ECU plugs could also cause the O2 sensor problem.

Edit: yes, it can take up to a day for the O2 codes to re-appear.

Car is second hand. Hopefully the codes don't come back after some driving. Even after buying this car I noticed it always had an mpg below 30. But when I tested the 02 sensors on my obd2 tool it says pass on both bank 1 sensor 1 and bank 1 sensor 2

Yes when i turn the key once just before starting engine, it does appear to have an eml light but is this normal? Then immediately goes off when engine is started

Jjb0800 wrote: ↑Sat Jan 29, 2022 10:04 am Yes when i turn the key once just before starting engine, it does appear to have an eml light but is this normal? Then immediately goes off when engine is started

Yes, this is normal.

It shows you the warning light is working when you first turn the key

I ask about the engine light because I have seen all too often previous owners "tamper" with this light. Blank it off, remove it, whatever. Just to hide a problem.

Can you see the fuel trims on your scanner?

Can you see live data of bank1 sensor 1? Should oscillate between just under 1 volt and just over 0 volts. My bet is it is just a flat line.

Hi what is a fuel trim?

The engineers set a theoretical and ideal fuel consumption rate for that engine. If the engine ECU has to add or take away more fuel to get the engine to run correctly that's called trimming.

It is expressed in % and is a positive or negative value.