Check Engine Light Flashing When Accelerating

It’s quite concerning to see the check engine light flashing when accelerating as it can make it difficult to control the car’s speed.

A car’s CEL can flash while accelerating due to a cylinder’s misfire, damaged exhaust system, bad throttle body sensor, and ignition problem.

Since CEL’s flashing while accelerating is a serious issue, you shouldn’t continue driving the vehicle. Instead, diagnose the car using a scanner and solve the underlying issue before it damages the catalytic converter.

Misfire in the cylinders is the most obvious reason for causing the check engine light to flash when accelerating.

Misfires can occur for many reasons, including putting the wrong fuel in the fuel tank, wearing out the ignition coil, and damaging the ECU.

It affects the emission control system, fuel efficiency, and the car’s overall performance. Scan the system by an expert mechanic, and you’ll have error codes P0301, 302, and 303. Below are some common causes of CEL flashing when accelerating:

Damaged Exhaust System

Check engine light can flash continuously when accelerating due to a faulty exhaust system, which results in an engine misfire.

It can happen if one or more cylinders don’t get enough sparks from the ignition system or air doesn’t pass from the intake system to the cylinders. A damaged fuel injector can also cause this issue.

Damaged Catalytic Converter

If you ignore the engine misfire, it can turn into a severe issue and damage the catalytic converters. If the check engine light flashes briefly and stops when accelerating moderately hard, it’s an obvious sign of a bad catalytic converter.

Damaged Throttle Body Sensor

If the engine starts stuttering and the check engine light blinks on and off when you accelerate, the throttle body sensor may get damaged.

If so, neglecting the issue can activate the limp mode and drive homes, making the car inefficient. If the throttle body sensor is responsible, you may have to clean or replace it to restore functionality.

Ignition Problem

Various ignition system problems, like bad wires and damaged spark plugs, can cause CEL to flash when accelerating.

It can also disturb the engine to maintain proper air and fuel mixture and activate the check engine light. It can end up causing increased emissions and poor engine performance.

Damaged Fuel Delivery System

The fuel delivery system supplies the tank’s fuel to the engine and maintains proper delivery at a certain pressure.

However, it can malfunction due to fuel pump failure, damaged fuel injectors, blocked fuel filters, and vapor leaks.

It can drop the fuel level rapidly and cause the CEL to flash when accelerating. Though it brings minor consequences compared to other potential reasons, it requires deep diagnosing to fix this problem.

The Bad ECU

The camshaft position sensor monitors the car’s camshaft position and speed. It then delivers the information to the ECU, which controls the fuel amount that enters the combustion chamber and the timing of the fuel ignition.

When you accelerate, the car must adjust the ignition timing and fuel intake to a high degree. However, if the camshaft sensor gets damaged, it can deliver wrong information to the ECU and disturb the ignition timing. Hence, the check engine light may start flashing when you accelerate.

Faulty Oxygen Sensor

The oxygen sensor monitors exhaust gases to balance the fuel-air ratio. If broken, it can get a lean or rich mixture and will misfire when accelerating and blowing the check engine light.

Vacuum Leaks

An air-fuel mixture is messed up in an air vacuum leak, usually in the intake manifold or hoses, which leads to poor acceleration. That asymmetry can cause fires, lighting up a check engine light.

Risk of Driving with Check Engine Light Flashing When Accelerating

If the check engine light flashes red, you should stop driving the car immediately as it indicates that the damage is already done.

However, you can drive the car to the mechanic if the light flashes orange. It sometimes indicates less serious problems like low fluid levels.

Engine misfire is the most common reason for checking engine light flashing. It can happen due to a failing spark plug coil overheating the catalytic converter.

It can then melt the inside of the converter plug in the exhaust system and affect the combustion chamber.

While changing four spark plug coils can cost $160, replacing the catalytic converter and oxygen sensor can cost around $900. So you shouldn’t drive with the check engine light flashing until you determine what you are ignoring.

In terms of safety, it’s dangerous to drive with an engine misfiring. It might not let you get out in front of traffic and can cause an accident.

Depending on the reason for CEL’s flashing, your car stops running immediately and blocks the traffic. You may also need to tow your car.

What To Do If Check Engine Light Flashes When Accelerating?

CEL’s flashing when accelerating mostly indicates a serious problem with the engine, and ignoring the issue can bring severe consequences. So, if your car’s CEL flashes when accelerating, stop driving the vehicle at least at high speed.

Slow down the car and safely drive to the nearest auto repair shop. If you are more concerned, tow the vehicle to the service center or home garage.

You can also call for emergency help. However, driving with CEL flashes can increase the repair cost by hundreds to thousands.

However, the repair cost may vary depending on the exact problem. For example, replacing the full set of spark plugs can cost around $100 to $150, while changing the fuel injector can cost up to $500.

How To Fix Check Engine Light Flashing When Accelerating?

Replacing a flashing check engine light when accelerating is typically a matter of resolving engine ignition, fuel, or exhaust problems. Here’s a step-by-step guide:

1. Check And Replace Spark Plugs or Ignition Coils

Out-of-date spark plugs or faulty ignition coils cause most engine fires, particularly under acceleration. Check for these parts and replace damaged parts. This is often a cheap fix and can fix a misfire if that’s your big issue.

2. Inspect Fuel System Components

Fuel injectors, fuel pumps, or filter failures can keep the engine from getting enough fuel. Inspect these parts for clogs, leaks, or damage. Wash or replace bad fuel injectors, and change the fuel filter if you haven’t replaced it recently.

3. Test the Oxygen Sensor

An oxygen sensor gone bad will upset the air-fuel mixture, leading to misfires and a check engine light. Identify oxygen sensor problems with an OBD-II scanner. If the sensor is bad and needs to be replaced, it should give you optimal fuel balance.

4. Examine the Catalytic Converter

Fires dump unburned fuel into the catalytic converter, which will overheat and corrode. If you smell sulfur/”rotten egg” smell, it might be a catalytic converter problem. Replacement costs a lot, but a healthy catalytic converter can help the engine run better and emit less pollution.

5. Look For Vacuum Leaks

If there’s a vacuum leak, that’s going to cause the air-fuel mixture to go out of whack and misfire. Check for cracks, loose fittings, or leaks on hoses and intake manifolds. It will perform better if you replace old hoses or plug leaks.

6. Diagnostics With OBD-II Scanner

If you have access to an OBD-II scanner, it reads check engine light diagnostic trouble codes (DTCs). This is a tool to identify the problem, making it quicker and more accurate to fix.

When the check engine light returns, drive the car again and see if the problem has been corrected. If the light still goes off, get it to a mechanic before it is too late.

FAQs on Check Engine Light Flashing When Accelerating

Final Words

If your car’s check engine light flashes when accelerating, park the car in a safe place instead of driving. If you have a scanner like OBDII, use it to determine the error code that may cause the issue.

If you don’t have the tool, consult with an expert mechanic. Either way, you should bring the car to the nearest service center. CEL flashing when accelerating isn’t a minor issue you can ignore for a long time.