Problem: HF code after 18 minutes. Took about 1 hr 20 min to complete any cycle. Last 1 sec on timer took about 20 min. No/almost no water coming from sprayer nozzle at 12 o'clock position behind glass.
Testing: Diagnostic test showed no errors, however, C:03 took 6 minutes (60-90 seconds is normal). Advised to replace flowmeter which didn't help. Replaced Inlet Valve which fixed all problems.
Understanding: The new valve increased water flow by about 5x-10x. Water sprayed from the nozzle where none/almost none was seen before. A much louder, rushing water sound could be heard. Diagnostic C:03 took about 70 sec. Because more water was now entering the machine, and at a faster rate, HF was not generated and the cycle time was reduced to 45-65 min, depending on load size. **A diagnostic test that doesn't show any errors doesn't necessarily mean everything is working properly.
Cost about $60. Would have been $600 using a plumber, if I was lucky.