Check engine light and traction control light on and car shaking? This alarming combination typically indicates a serious engine misfire that requires immediate attention. While you may be able to drive short distances with a solid check engine light, a flashing light with shaking means you should stop driving immediately to prevent catalytic converter damage and potential safety hazards.
Why Both Warning Lights Illuminate Together
When both check engine light and traction control light illuminate simultaneously while your car shakes, it’s not a coincidence. Modern vehicles have interconnected systems where one malfunction can trigger multiple warning lights.
The primary reason both lights appear together is that many manufacturers program their vehicles to automatically disable the traction control system when engine performance issues are detected.
Check Engine Light Basics
The check engine light (CEL) is designed to alert you when your vehicle’s onboard computer detects a problem that could increase emissions or damage engine components. When this light appears, it can display in two ways:
- Solid light: Generally indicates a less urgent issue that should be checked soon
- Flashing light: Signals a severe problem (typically an engine misfire) that requires immediate attention
Traction Control Light Explained
The traction control light typically appears as a car with skid marks or the letters “TC” or “ESC” (Electronic Stability Control). This light serves two purposes:
- It briefly illuminates when the system is actively preventing wheel slip
- It stays on continuously when there’s a malfunction in the system or when the system has been automatically disabled due to another vehicle issue
In Toyota vehicles specifically, the traction control system automatically turns off when the check engine light is on, displaying both the “TRAC OFF” light and check engine light simultaneously.
Common Causes of Engine Light, Traction Control Light, and Shaking
1. Engine Misfires
The most common cause of this troubling trio is an engine misfire. A misfire occurs when combustion fails to happen properly in one or more cylinders. When a cylinder misfires, it creates an uneven power delivery that causes the engine to shake or vibrate noticeably. Common causes of misfires include:
- Worn or fouled spark plugs
- Faulty ignition coils
- Damaged spark plug wires
- Clogged fuel injectors
- Vacuum leaks
2. Wheel Speed Sensor Issues
Faulty wheel speed sensors can trigger both warning lights. These sensors monitor the rotation speed of each wheel and provide crucial information to both the traction control system and the engine management system. When they malfunction, they can cause:
- Erratic traction control behavior
- Check engine light activation
- Rough shifting in automatic transmissions
3. Low Tire Pressure
Surprisingly, something as simple as low tire pressure can cause both warning lights to illuminate in some vehicles. Underinflated tires affect wheel speed readings and can trigger the traction control system, while also potentially causing the check engine light to activate due to increased load on the engine.
4. ABS System Problems
Since the traction control system often works in conjunction with the Anti-lock Braking System (ABS), problems with the ABS can affect both systems and trigger multiple warning lights.
5. Emissions Equipment Issues
Problems with components like the EGR (Exhaust Gas Recirculation) valve or purge valve can cause engine performance issues that trigger both warning lights. A stuck open EGR valve allows excessive exhaust gases into the combustion chamber, causing incomplete combustion and misfires.
Is It Safe to Drive With These Symptoms?
The safety of driving with both warning lights on and car shaking depends primarily on the nature of the check engine light:
When to Stop Immediately
You should pull over and stop driving if:
- The check engine light is flashing (not just solid)
- The car is shaking significantly
- You notice unusual engine sounds, smoke, or smells
- The vehicle is overheating
- There’s a significant loss of power
A flashing check engine light with shaking indicates a severe misfire that can damage your catalytic converter within minutes. Raw, unburned fuel entering the catalytic converter can cause it to overheat (potentially reaching 1200 degrees) and even start glowing, creating a fire hazard.
When Limited Driving May Be Possible
You might be able to drive a short distance if:
- The check engine light is solid (not flashing)
- The shaking is mild
- The vehicle otherwise operates normally
- You’re only driving to a nearby repair facility
Even in these cases, drive gently and avoid hard acceleration to minimize potential damage.
Diagnosing the Problem
Using an OBD-II Scanner
The most effective way to diagnose the specific issue is to use an OBD-II scanner to read the error codes stored in your vehicle’s computer. Common codes you might see include:
- P0300-P0308: Cylinder misfire detected
- P0856: Traction Control Input Signal
- P0858: Traction Control Input Signal Circuit High
Many auto parts stores offer free diagnostic scanning services if you don’t have your own scanner.
Professional Diagnosis
While code reading is helpful, a professional mechanic can perform more thorough diagnostics including:
- Spark plug inspection
- Fuel pressure testing
- Compression testing
- Sensor voltage testing
- Vacuum leak detection
Solutions for Check Engine Light, Traction Control Light, and Shaking
The solution depends entirely on the underlying cause, but common fixes include:
For Misfire-Related Issues
- Replacing spark plugs and ignition coils
- Cleaning or replacing fuel injectors
- Repairing vacuum leaks
- Replacing damaged wiring
For Sensor-Related Issues
- Cleaning or replacing wheel speed sensors
- Repairing damaged wiring or connectors
- Replacing faulty ABS components
For Tire-Related Issues
- Properly inflating all tires to the recommended pressure
- Replacing damaged tires
- Performing wheel alignment
Preventive Maintenance to Avoid These Issues
To reduce the likelihood of experiencing these warning lights and symptoms:
- Follow your vehicle’s maintenance schedule for regular service intervals
- Replace spark plugs according to manufacturer recommendations
- Check tire pressure monthly and before long trips
- Have your battery and electrical system checked during routine maintenance
- Address minor issues promptly before they develop into major problems
When to Seek Professional Help
While some causes might be simple to fix (like tightening a loose gas cap or inflating tires), most issues that trigger both warning lights with shaking require professional attention. You should seek professional help if:
- You’re not comfortable performing diagnostic work
- The check engine light is flashing
- The car is shaking significantly
- You’ve tried simple fixes and the problem persists
- You don’t have the proper tools to diagnose the issue
Remember that continuing to drive with a flashing check engine light and shaking can cause expensive damage to your catalytic converter and other engine components. The cost of a tow to a repair shop is far less than the cost of a new catalytic converter or engine repairs.
Don’t gamble with your vehicle’s health or your safety. When both warning lights illuminate and your car shakes, take it seriously and address the issue promptly to avoid more extensive and expensive repairs down the road.