Updated: Feb 5
✔ This article has been fact checked.
If you have a Subaru you may have noticed the check engine light come on, if you scan the ECU with an OBD reader you may have come across the P0000 fault code. You may also notice the cruise control disable and the cruise light illuminates
Generally speaking, a P0000 code means there is no fault or the OBD reader cannot read the fault code and is putting this code in place of the actual fault code.
To fix this you need to use an OBD scanner compatible with Subarus to correctly read the diagnostic code. However, sometimes the code still shows up, even after using another OBD scanner.
Table of Contents:
What a P0000 Code Means
The P0000 fault code can be quite perplexing as it implies no diagnostic trouble codes (DTCs) detected by the system. However, this code appearing on your onboard diagnostic (OBD) scan tool usually means one of two things.
Firstly, it could indicate that your scanner is incompatible with your vehicle's diagnostic system.
Secondly, it could mean that there is an underlying fault code that is not being detected by the scanner you're using and is being hidden beneath the P0000 code.
In the case of a Subaru, there could be other causes (as shown in the next section).
When the computer in your vehicle detects a problem, it triggers the malfunction indicator lamp (MIL), commonly referred to as the check-engine light. This serves as a warning sign to vehicle owners that something is not functioning as it should.
When a problem is detected, most cars will switch to an open loop mode, also known as "limp mode", which limits the power and performance of the engine. This is designed to prevent further damage to the engine and ensure that the vehicle can still be driven.
However, if the P0000 fault code is displayed and the check engine light or limp mode is activated, there is likely an issue that remains undetected. In such cases, you'll need to use a more advanced scan tool to uncover the fault code.
These advanced scan tools have more comprehensive diagnostic capabilities and can identify the issue that is being masked by this trouble code.
Watch the video below to learn more about a P0000 fault code.
There are a few potential causes of this fault code on Subaru vehicles.
Contact With Cruise Switch During Vehicle Startup
According to the owner's handbook, accidental contact with the cruise switch during vehicle startup may be to blame for the CEL and flashing cruise light. However, this is not always the cause of a P0000 code.
Incompatible OBD Scanner
A P0000 DTC is typically caused by an incompatible OBD reader (such as a universal or multipurpose scanner). You will need a specialised or professional OBD scanner to correctly read fault codes on your Subaru.
Fuel Cap Loose
Modern Subarus may trigger the check engine light if the fuel cap is open or loose. This could cause the P0000 fault code to be triggered if the OBD scanner is a multipurpose non-compatible scanner.
Although this is not always the cause, its worth ensuring the fuel cap is properly secured. When you refuel your Subaru, make sure that you properly slide the gas cap on perfectly, push it in slightly and turn away.
How to Fix
To fix the code on a Subaru, you can try the following steps.
Avoid contact with the cruise control switch during startup. The cruise control system on a Subaru can be sensitive and may throw a fault code if the button is bumped or pressed during startup. Avoid contact with the switch to prevent this until the engine has fully started and stabilized.
Use a compatible OBD scanner. An OBD (On-Board Diagnostics) scanner can be used to diagnose the fault code and determine the cause of the problem. To ensure the best results, use a scanner compatible with your specific model and year of Subaru.
Ensure you properly tighten the fuel filler cap. A loose fuel filler cap can cause problems with the evaporative emissions system and trigger a fault code. Make sure to properly tighten the fuel filler cap after fueling your vehicle.