Toyota 2001 Avalon

failed inspection (NJ) due to ck eng light on - codes P0171,P0174, P0330 - went to NJ State authorized repair shop and they told me they have to hook car up to find out what the codes mean - they want $95.00 to do that + whatever the repair will cost. I am on a fixed income and every dollar counts. Does this make sense that they cannot tell me what has to be fixed???

Unfortunately the answer is yes. The check engine codes just offer a clue to what may be wrong. It takes an experienced mechanic to actually repair the problem. The CEL system is good but it’s far from perfect.

P0171 - System lean Bank 1 Which is an 02 sensor Pre Cat I believe.

P0174 - System Lean Bank 2 o2 Sensor After Cat

P0330 - The P0330 code is for the knock sensor on the left bank.

The sensor has a short, open circuit, is loose or there is an issue with the wiring. The ECU via the trouble code is indicating it cannot read any sensor output.

So while you have the breakdown of the codes…you then need to feel out which ones are actual “valid codes” I would start by deleting all the codes and see which ones come back. Then act on each code one by one.