What Codes Will This Page Cover?
On this page, you’ll find more about the following fault codes:
- P0645 A/C Clutch Relay Control Circuit
- P0646 A/C Clutch Relay Control Circuit Low
- P0647 A/C Clutch Relay Control Circuit High
Who Has the Lowest Price?
Some service centers will give you an online estimate to compare. Why drive around Town!?
What Is the P0645 Code?
Symptoms
Causes
Seriousness
Can I Still Drive?
Diagnose
Difficulty of Inspecting
Get Additional Help
More About the P0645 Code
The P0645, P0646, and P0647 codes all have to do with your vehicle’s A/C clutch relay control circuit, which has to do with your car’s air conditioning system. The A/C compressor clutch maintains pressure in your vehicle’s A/C system through a relay that your vehicle controls with the powertrain control module (PCM) or engine control module (ECM). Code P0645 indicates that your vehicle is noticing an issue with your clutch relay control circuit, which delivers that information between the PCM and the clutch. In addition, P0646 indicates that the circuit voltage is low, while P0647 indicates that the voltage is high.
What Are the Symptoms of a P0645 Code?
The most common symptom of the P0645, P0646, and P0647 codes is the check engine light turning on. If you have other malfunction indicator lights referring to your vehicle’s air conditioning system, you’ll likely see those lights turn on as well. If you turn on your air conditioner, especially if you’re driving in hot weather, you’ll also probably notice that your A/C isn’t working properly, whether it doesn’t work at all or only works poorly.
What Are Some Causes of a P0645 Code?
The A/C compressor driver or A/C compressor control relay are the most common causes of these diagnostic trouble codes. If you’re seeing this trouble code, it’s usually because one of these components within your vehicle is broken in some way. However, the problem may lie in your vehicle’s electrical connection throughout the A/C compressor control relay system, whether it’s faulty wiring, problems with the connector pins, or issues with your wiring harness. Issues with the Controller Area Network bus (CAN bus) or a loose control module ground strap can also result in the P0645, P0646, and P0647 codes.
How Serious Is the P0645 Code?
The P0645, P0646, and P0647 codes only refer to a problem with your vehicle’s air conditioning. If you’re only dealing with the P0645 OBD-II trouble code, you don’t have to worry about the code suddenly disabling your car or becoming a severe issue. However, especially if you live in a warmer climate, it’s still important to fix the problem soon. The compressor clutch relay may not seem like a hugely important problem, but it’s definitely frustrating and can make it more difficult to drive your vehicle in general. Plus, getting help with this problem also allows you to make sure there aren’t any other problems that you’ve accidentally overlooked.
Can I Still Drive with a P0645 Code?
You can often physically drive with active P0645, P0646, and P0647 diagnostic trouble codes (DTCs). The compressor clutch relay control sending out an improper signal is not something that will usually cause your vehicle to stop functioning effectively, and it doesn’t usually have to do with a control module error that may result in more serious problems down the line. However, given how frustrating it can be to drive your car without air conditioning, it may be quite valuable to take the diagnosis time necessary to fix it.
How Easy Is It to Diagnose a P0645 Code?
The diagnostic process often depends on the core problem of DTC P0645, P0646, and P0647. In some cases, you may need more advanced equipment and a more robust troubleshooting process to figure out the core problem. In others, it may only take about an hour of labor or less to figure out the problem and fix it. That being said, if you’re not especially knowledgeable about various components of your vehicle, you might not be able to avoid common mistakes that could arise during this process. Talking to an expert is generally recommended instead of trying to dive in headfirst.
How Difficult Is It to Inspect a P0645 Code?
As with the diagnostic process, the inspection process can be tricky for the P0645, P0646, and P0647 codes. You need access to technical service bulletins, basic and advanced tools, specific information about your engine type, knowledge of the voltage requirements for your circuit, and much more. If you’re not comfortable figuring out these components of your engine, the rates at auto repair shops will definitely be worth your time and money.
Need Additional Help with Your P0645 Code?
Most people eventually need help with the P0645, P0646, and P0647 codes. Even if you start out not needing a fix, over time, it will probably become frustrating enough that you’ll want to fix the underlying problem.
This is why it’s a great choice to find an auto repair shop in your area. Local repair shops can help you fix this problem and work on anything else you might be concerned about at the same time, like testing your battery voltage.
Additionally, some people like to know all the issues they may be dealing with before they bring their vehicle in. If your scan tool shows other codes besides the P0645, P0646, and P0647 codes, the OBD-II database at KBB.com is a great starting point. Use this database to learn more about these codes and what they might mean for your vehicle so you know what you’re dealing with early on.
P0645 Q&A
Common Error Codes
Browse All OBD-II Codes
Get Recall Alerts
All recalls are considered serious. Stay safe. Take care of any recalls ASAP. The good news? Recall repairs are free when performed at a local dealer.