Seeing your check engine dash light turn on can be unnerving, especially if you don’t have a code scanner handy.
What could be the problem?
Can you keep on driving?
The good news is that there are some ways to view engine light codes without a scanner tool.
There is a caveat, though.
These methods won’t apply to all cars, especially more recent vehicles. But it does not harm to try.
Keep reading to learn more about how to check engine light codes without a scanner.
This Article Contains
- How to Check Engine Light Codes Without a Scanner
- What Does Your Check Engine Light Mean?
- What Are the Risks of Driving With a Lit Check Engine Light?
- How to Reset or Clear Codes Without a Scan Tool
- What Are the Types of OBD II Codes?
How to Check Engine Light Codes Without a Scanner
Here are some methods to extract engine light codes without a code reader or scanner. It’s important to note that reading OBD codes using these methods may take a few attempts to capture them, especially if there are multiple codes:
A. Use the Ignition Key
Turn the key in the ignition ON and OFF 3-5 times without cranking the engine.
End with your ignition in the ON position. In some cars, you can stop when all the dashboard lights illuminate. Then, they will turn off except one—usually the SES light (Service Engine Soon).
Check the odometer display. The type of check engine code depends on the vehicle’s diagnostic system:
- An OBD2 system will display p-codes.
- An OBD1 system will display a series of blinks and pauses. Observe these:
- Blinks = digit
- Pause = separates digits
- Example: blink blink PAUSE blink blink blink blink = 24 (on GM cars, this OBD code implies a speed sensor error)
Once you have the trouble codes, check what each diagnostic code means.
2. Use the Odometer Buttons
Hold down the odometer’s trip and reset buttons at the same time. Then, with the buttons still pressed, turn the ignition to the ON position.
Note: You may need to flip the ignition ON, OFF, ON a few times.
Leave the key in the ON position and release the odometer buttons. The error code (if any) should appear in the odometer display.
3. Use a Paper Clip (for OBD1 Cars)
This method is for older cars with the OBD 1 diagnostic system. Make sure the car is off before you start.
- Find the 2 terminals at the OBD port under the steering wheel (refer to the owner’s manual for the port’s location).
- Connect the terminals with a paper clip or jumper wire.
- Turn the ignition to ON without cranking the engine. Then, record the pattern of blinks and pauses to get the OBD code plaguing your car.
4. Let an Expert Do It
If you can’t get a scanner and none of the other methods work, your last resort is to get a mechanic to check and resolve your diagnostic code.
Even better, get a mobile mechanic to do it so you don’t have to risk driving a problematic car to a workshop. The fault code should automatically clear after the mechanic has handled the necessary car maintenance or repair.
Retrieving a check engine light code is important to help you figure out what’s wrong with your vehicle. But knowing how to react to a lit engine light is even more so.
What Does Your Check Engine Light Mean?
A lit check engine light (CEL) signifies that the engine control unit (ECU) has identified a problem that needs fixing. The condition of the light and how you respond to it matters:
- Solid yellow or orange CEL: The ECU has detected a malfunctioning component or system. The problem isn’t immediate but should be fixed soon. Don’t drive more than 100 miles before getting it resolved.
- Solid red CEL: The detected problem must be fixed sooner rather than later, but it isn’t catastrophic. Do not delay a repair.
- Flashing CEL: The identified problem is immediately severe and could cause engine failure. You should pull over and stop your car to get help.
Here are some common reasons for a lit check engine light:
- Loose gas cap
- Bad O2 sensor (oxygen sensor)
- Failing catalytic converter
- Faulty MAF sensor
- Bad spark plug or spark plug wires
- Faulty ignition coil
- Damaged exhaust pipe
- Low fluid levels
- Electrical issues
Let’s discover what can happen if you ignore the check engine warning light.
What Are the Risks of Driving With a Lit Check Engine Light?
Disregarding a lit check engine dash light isn’t advisable. The car’s computer throws a check engine code for a reason. Here’s what could happen:
- Reduced engine performance: The CEL lights up when there’s an engine issue. If ignored, it can lead to reduced performance and fuel efficiency as the engine isn’t functioning optimally.
- Engine stalling: In more severe conditions, ignoring a CEL can cause sudden power loss. This is especially dangerous in heavy traffic.
- Compromised safety: Modern vehicles rely on many sensors. Any sensor malfunction could adversely affect safety systems like traction control, ABS, etc.
- Impaired emission controls: Many CEL warnings are tied to emission system issues (like a faulty O2 sensor). Ignoring these can increase emissions that contribute to harmful environmental pollutants. You may also fail emissions standards in certain states.
- Increased repair costs: Ignoring or delaying a resolution for the CEL can escalate the problem, leading to more significant and costly engine issues (such as a damaged catalytic converter).
Next, let’s discuss clearing codes.
How to Reset or Clear Codes Without a Scan Tool
It’s possible to clear engine light codes and reset the engine light without a scanner, though these methods may not work on all cars. However, just clearing codes and not fixing the underlying issue means the related diagnostic trouble code (and CEL) will return.
Here are three ways to clear codes without a scanner tool:
- Battery Disconnect:
- Make sure the engine is off.
- Disconnect the negative battery terminal and remove it from the battery post.
- Wait for about 15 minutes before reattaching the battery.
- Crank the engine to see if the check engine light goes away.
- Engine cycling: To do this, you simply have to turn the ignition ON and OFF several times.
- ECU Fuse Removal: Find the fuse for the ECU and temporarily remove it. Note that this method only works on older vehicles and (important!) might wipe out all the engine codes.
What Are the Types of OBD II Codes?
A diagnostic trouble code (DTC) can be:
- A generic code that applies across all cars with ODB2 (OBD II) systems
- An enhanced code, which is manufacturer-specific
For OBD2 systems, you’ll need an OBD2 scanner (OBD II scanner) for a comprehensive view, though most lower-end tools won’t read OBD1. However, if the scanner reads older OBD1 protocols, it’s almost always compatible with OBD2. To read an enhanced code, you’ll likely need a manufacturer-specific code reader.
If you use a code scanner to extract p-codes, you may see several error code statuses:
1. Pending Codes
Pending codes won’t trigger your check engine light. They’re an early warning sign that abnormal behavior has been detected in a vehicle system, but the issue hasn’t been confirmed through repeated occurrences. These codes can be cleared with an OBD scanner.
For example, if your car hits a bump and the spark plug wire temporarily loosens, you might get a P0300 engine code for a misfire. But since it only happened once, it remains a pending DTC code. A pending fault code can become a confirmed code (stored code) or a permanent code.
2. Confirmed Codes
A confirmed engine code or stored code means that a problem has been confirmed through multiple occurrences and that your car needs attention. An OBD scanner can clear these codes.
Following the spark plug wire example, misfires will repeat if the wire remains disconnected, so the P0300 trouble code is now confirmed.
3. Permanent Codes
Permanent codes apply to vehicles 2010 and newer. They’re like confirmed codes, except a scanner can’t clear them. They’re usually related to the emission system and were introduced to prevent clearing codes before an emission test.
Permanent codes can only be cleared once the issues have been resolved and enough data has been gathered through specific drive cycles for that specific vehicle (e.g., drive for 5 minutes at 30 mph, then drive another 5 minutes at 5 mph).
Get Your Trouble Code Cleared with AutoNation Mobile Service
The check engine warning light is there for safety reasons, and ignoring it can lead to severe consequences. While it’s possible to check engine light codes without a scanner, it isn’t ideal, especially if there’s more than one DTC code.
You could buy an OBD1 or OBD2 scanner.
But to simplify things, why not get AutoNation Mobile Service to help?
We’re a mobile auto repair and maintenance solution available seven days a week. We can diagnose and fix your check engine light right from your driveway.
Get in touch with us, and we’ll send our expert mechanics to help you with all your car maintenance needs.