What do P0016 and P0018 together mean?

They are clues to investigate, not a parts diagnosis. For the Ford vehicles and calibrations covered by Ford’s 2020–2023 OBD document, P0016 is crank/cam position correlation for Bank 1, and P0018 is the corresponding correlation code for Bank 2. [S1]

If that definition applies to your vehicle, both banks have had a correlation code recorded. That does not establish whether there is one shared cause, separate causes, or a failed part. Nor should you assume the same bank assignments apply to another make, engine, or model year: the cited Ford document limits its definitions to the vehicles and calibrations it covers. [S1]

A useful first step is to identify the exact vehicle and record when and how the codes appeared. A qualified diagnostician can then check the applicable service information and decide what evidence to examine. Avoid replacing a part based only on the code pair.

Make a compact vehicle and scan record. Include:

1. Year, make, model, and engine.
2. The exact codes as displayed, including whether each is current, pending, or stored, if your scan tool shows that information. Copy the labels as shown rather than guessing.
3. Freeze-frame information for each code, if available. Copy the values as displayed rather than interpreting them. Note when the codes were read and whether they returned after being cleared, if that has already happened.
4. What you noticed around the time the codes appeared, such as a change in how the vehicle ran or an event you think may be relevant. Record observations, not a diagnosis.

This information helps the shop confirm whether the code definitions and bank assignments apply to your exact vehicle. The cited Ford document does not provide a diagnosis for every vehicle or establish the cause of a particular code pair. [S1]

Describe the pattern as a question, not a conclusion. For example, you can send:

“Vehicle: [year, make, model, engine]. Codes: P0016 [status shown by scanner] and P0018 [status shown by scanner]. They were recorded [when/how discovered]. Freeze-frame details available: [copy values or ‘not available’]. Could you confirm these codes’ definitions and bank assignments for this exact vehicle, then use the applicable service information to determine whether the records suggest a shared area to investigate or separate issues? What evidence supports the next diagnostic step?”

That wording invites the professional to assess both possibilities without declaring that a shared reference, component, or other cause is present. The code pair alone does not establish that. [S1] Ask the shop to explain what findings lead to any proposed repair and how those findings relate to both codes.

Start by confirming the vehicle-specific definitions and bank assignments; the cited definitions are limited to certain Ford vehicles and calibrations, not every vehicle. [S1] Next, ask whether the shop has the code status and available freeze-frame context, and what applicable service information it will use. Then ask what evidence would distinguish a shared concern from separate issues, and what the proposed next check is intended to establish.

You do not need to provide a parts diagnosis or perform tests to make this discussion useful. Avoid treating the code pair as proof that a particular part has failed. If you lack scan details, say so; a qualified professional can determine what information is available and what diagnostic steps are appropriate for the vehicle.