Here’s a link to the FSM multimeter tests, continuity, resistance and voltage drop.
If you’re unfamiliar with these try searching YouTube with eg “the trainer resistance test” and so on.
https://www.dropbox.com/sh/6w38xtm9lv5y ... vPTBa?dl=0Most of these harness checks refer to a single wires pins, plug to plug, with the harness disconnected from the eg ecu and component, this usually requires an added jumper wire to complete the circuit with the multimeter inline. Of course you can check for continuity between plug pins or ground to find short circuits from worn insulation.
Where relevant testing the component and or the ecu will be covered in the diagnostics.
P0122 P0607 P2109 P2127, P2135 all refer to the accelerator pedal/throttlebody, either component can fail, or the harnesses between the component, ecu and ground.
I’d approach the diagnostics in numerical order since there’s definite taxonomic intent behind the codes, thus the cascading order: fails startup self test, potential failed components or connections.
Try hooking up the secondary air gear as per stock, reset the ecu then read your codes on the odometer again.
I’d be extremely dubious about taking action on a DTC from a third party non SSM obdii reader, especially for a code not listed in your year model FSM. It could be a false indication. The odometer DTC check gets to all factory codes including the canbus and more.
Alternatively if a related code is present, your choices are to replace the faulty components (used parts being financially viable) or since your Postfl ecu is aftermarket tuneable, get the DTC’s disabled and in the case of a stuck open valve, place a welch plug in the air pipe or use a blanking plate to seal the air pipe from exhaust gas.
There’s also the chance that DTC was thrown from a low battery condition.
Here’s a link to your Postfl 2.5i DTC diagnostic screenshots, work in progress.
https://www.dropbox.com/sh/9ly1xwyv3t8d ... eyYma?dl=0