Chevy Express Flashing Check Engine Light: Diagnosis

The check engine light indicates that you need to service a vehicle soon. If your Chevy Express has a flashing check engine light means that there is a catalyst damaging misfire (it can damage the catalytic converter and O2 sensors).

If your van has a flashing check engine light, it means you need to service the engine now. So don’t drive your van.

Chevy Express Flashing Check Engine Light

Table Of Contents

Blinking Check Engine Light Diagnosis: Chevy Express

Pulling Trouble Codes

There will always be trouble codes associated with the Chevy Express’s check engine light flashing. The first thing you want to do is look them up with an OBD II scanner.

A code scanner is cheap.  Use it to discover exactly why your van’s computer flashed this light. Also, most parts stores will scan your vehicle for free if your check engine light is on.

Check Engine Light Flashing Causes

A misfire is the number one reason your Express’s check engine light will flash. 

Ignition System

Chevy Express Blinking Check Engine Light Diagnosis

Your van’s ignition system consists of spark plugs, plug wires, and ignition coil packs (older vehicles have a distributor that has the same function as coil packs).  These parts work in concert to ignite the fuel in the combustion chamber at just the right time.

Random Multiple Misfire

P0300 indicates that your Express’s engine is misfiring, but it can’t detect which cylinder it’s coming from.  This code is often thrown when there is a fuel issue, a timing issue, and not just bad ignition components (most likely).

Cylinder Specific Misfire

The plug on the left was causing the check engine light to flash and threw a cylinder-specific misfire code.

If the only code your van has is for a cylinder-specific misfire. Start with pulling the plug and taking a look at it.

These trouble codes correspond with a specific cylinder misfiring (cylinder number corresponds with its place in the firing order).  For example, P0301 indicates the Chevy Express is misfiring in cylinder 1.

Although it’s a bad sign when the service engine soon light flashes, when one of these codes comes up with it (and nothing else), it’s almost always one spark plug or ignition coil.  A leaking fuel injector can also cause a cylinder-specific misfire code.

There are other misfire-related codes as well, but those are the most common ones.

Fuel System Issues

A leaking injector can cause the check engine light to flash.

Keeping in mind that any engine needs air, fuel, and spark for ignition, your Chevy Express’s fuel system can often cause the engine to misfire.  It can run too lean or rich.  Alternatively, there could be too much.

  • Fuel Mixture:  If the engine is running rich or lean, the engine will misfire and throw the fuel mixture-related codes, such as P0171, P0172, etc…
  • Injector Issues:  A leaking fuel injector(s) can leak fuel into the combustion chamber at the wrong time, causing a catalyst-damaging misfire. When this happens, there will likely be a cylinder-specific misfire code.
  • Fuel Pressure– Too much fuel pressure can cause the injectors to leak. You’ll likely get a code that indicates the vehicle is running too rich and P0300.

Other Causes

While a majority of the time, the flashing check engine light is going to be caused by a misfire related to your Express’s ignition system or fuel system (as stated above), other issues can cause it. 

  1. Your timing chain could have jumped
  2. If your Express has VVT, it may be having issues. 
  3. EGR- The EGR system recycles burnt exhaust gasses back into the combustion chamber.
  4. Crank/Cam Sensor-  When the cam or crank sensors are not being read by the ECM/PCM, it’s impossible to get the ignition timing right.  If your Express does start at all, it’ll run rough.
  5. It could be a more serious mechanical issue, such as a bent valve, bad lifter, etc…


Can you drive the Chevy Express with a flashing check engine light?

Flashing Check Engine Light Meaning

Do not drive your Chevy Express with a flashing check engine light.

When your engine is misfiring, it dumps raw fuel into the exhaust.  This raw fuel can detonate, which causes damage to the catalytic converter and the exhaust system itself. 

Which is worse, a flashing or non flashing check engine light?

A flashing check engine light means you should not drive your Chevy Express until you’ve fixed the engine.

Check engine light flashing and the van is shaking

If your Express is shaking and the check engine light is flashing, it’s likely one or more of your van’s cylinders is misfiring.


We recommend that you don’t drive, if at all possible, until you diagnose and fix your Express’s flashing check engine light. 

Just pretend that it’s letting you know that it will cost you way more money to fix the problem if you keep driving it.