Check Engine Light Flashing?
A flashing check engine light is URGENT. Learn what it means and what to do immediately.
DO NOT IGNORE A FLASHING CHECK ENGINE LIGHT
Continued driving can cause catalytic converter and transmission damage
What Does a Flashing Check Engine Light Mean?
A flashing check engine light is your vehicle's way of telling you there's a serious problem that needs immediate attention. Unlike a steady check engine light, which indicates a less urgent issue that should be addressed soon, a flashing light means severe engine misfires are occurring that could damage your catalytic converter, transmission, or engine if you continue driving.
The most common cause of a flashing check engine light is an engine misfire severe enough that unburned fuel is reaching the catalytic converter. This can cause the converter to overheat and potentially melt internally, resulting in a very expensive repair. Additionally, severe misfires can affect transmission operation, causing harsh shifts or damage to internal components.
At Rohnert Park Transmission & Auto Repair, our ASE certified technicians use professional-grade diagnostic equipment to quickly identify the cause of your check engine light. We can read and interpret trouble codes, perform comprehensive testing, and provide honest recommendations for repair. Serving Rohnert Park, Santa Rosa, Petaluma, Cotati, and all of Sonoma County since 1997.
Immediate Actions to Take
Reduce Speed Immediately
Slow down to reduce stress on the engine and transmission. Avoid highway speeds.
Pull Over Safely When Possible
Find a safe location to stop. Continuing to drive with a flashing CEL can cause severe damage.
Turn Off AC and Accessories
Reduce engine load by turning off air conditioning, heated seats, and other accessories.
Check for Obvious Issues
Look for smoke, unusual smells, or fluid leaks. If present, stop immediately and call for help.
Call for Professional Help
Contact a certified mechanic for diagnosis. Do not continue driving extended distances.
Flashing Light
- •Severe engine misfire detected
- •Stop driving as soon as safely possible
- •Can damage catalytic converter
- •May affect transmission operation
- •Requires immediate professional attention
Steady Light
- •Less urgent issue detected
- •Safe to drive to repair shop
- •Should be diagnosed within days
- •Could be emissions-related
- •May fail smog inspection
Common Transmission-Related Diagnostic Codes
When your check engine light comes on, the computer stores diagnostic trouble codes (DTCs) that help identify the problem. Here are common transmission-related codes our technicians frequently diagnose:
P0700Transmission Control System Malfunction
MODERATE SEVERITYGeneral transmission fault detected. Indicates the transmission control module has stored a fault code.
P0715Input/Turbine Speed Sensor Malfunction
MODERATE SEVERITYThe transmission input speed sensor is sending incorrect signals or has failed completely.
P0720Output Speed Sensor Malfunction
MODERATE SEVERITYThe output speed sensor is malfunctioning, affecting shift timing and speedometer accuracy.
P0730Incorrect Gear Ratio
HIGH SEVERITYThe transmission is not achieving the correct gear ratio, often due to internal wear or solenoid issues.
P0740Torque Converter Clutch Circuit Malfunction
HIGH SEVERITYThe torque converter lockup clutch is not engaging properly, causing efficiency loss and overheating.
P0750-P0770Shift Solenoid Malfunction
HIGH SEVERITYOne or more shift solenoids are malfunctioning, causing harsh shifts or failure to shift gears.
Note: Multiple codes are often present. Professional diagnosis is required to determine root cause and proper repair sequence.
Is It Safe to Drive With a Flashing Check Engine Light?
NO - You should not continue driving with a flashing check engine light.
A flashing check engine light indicates a condition severe enough that continued driving could cause immediate and expensive damage. The most significant risks include:
- Catalytic Converter Damage: Unburned fuel from misfires can overheat and destroy your catalytic converter, one of the most expensive components to replace.
- Transmission Damage: Severe misfires can cause erratic power delivery, leading to harsh shifts and internal transmission damage.
- Engine Damage: Continued operation during misfires can damage pistons, valves, and other internal engine components.
- Safety Risk: A misfiring engine may stall unexpectedly, creating a dangerous situation in traffic.
If your check engine light starts flashing, reduce speed, find a safe place to stop, and call for professional assistance. The cost of towing is far less than the cost of the damage that can occur from continued driving.
Frequently Asked Questions About Flashing Check Engine Lights
What does a flashing check engine light mean?
A flashing check engine light indicates a severe engine misfire that could damage your catalytic converter or transmission. Unlike a steady light which indicates a less urgent issue, a flashing light means you should stop driving as soon as safely possible. The flashing pattern is specifically designed to grab your attention because immediate action is required.
Can I drive with a flashing check engine light?
You should not drive with a flashing check engine light except to reach a safe stopping point or nearby repair shop. Continuing to drive can cause catalytic converter damage (very expensive to replace), transmission damage, and engine damage. If you must drive, go slowly, avoid acceleration, and stop as soon as safely possible.
Is a flashing check engine light always transmission-related?
No, a flashing check engine light is usually caused by engine misfires, but it can indicate transmission problems especially if accompanied by shifting issues. Common causes include ignition system failures, fuel delivery problems, and yes, transmission malfunctions. Our diagnostic equipment can quickly identify the exact cause.
How much does check engine light diagnosis cost?
Diagnostic costs vary based on the complexity of the issue. We use professional-grade diagnostic equipment to read all codes and perform comprehensive testing. Call (707) 584-7727 for current diagnostic pricing. Many shops charge separately for diagnosis, but we apply diagnostic fees toward any repair you approve.
What's the difference between a flashing and steady check engine light?
A steady (solid) check engine light indicates a problem that should be addressed soon but isn't immediately critical - you can usually continue driving to your destination or a repair shop. A flashing light indicates a severe problem requiring immediate attention. The flashing is designed to communicate urgency and prevent you from ignoring a critical issue.
Can low transmission fluid cause a check engine light?
Yes, low transmission fluid can trigger check engine light codes, particularly transmission-related codes like P0700 or solenoid codes. Low fluid causes the transmission to malfunction, which the computer detects and reports. If your check engine light is accompanied by shifting problems, checking transmission fluid level is an important first step.
Will the check engine light reset itself after the problem is fixed?
Some check engine lights will turn off automatically after several driving cycles if the problem is resolved. However, many require manual reset with a diagnostic tool. We recommend professional diagnosis even if the light goes off on its own, as the underlying issue may still need attention and codes remain stored in the computer's memory.
What should I do if my car is shaking and the check engine light is flashing?
A shaking vehicle with a flashing check engine light is a serious situation. This usually indicates severe engine misfires. Pull over immediately when safe, turn off the engine, and call for assistance. Do not continue driving as this can destroy your catalytic converter and potentially damage your transmission. Call us at (707) 584-7727 for immediate assistance.
Check Engine Light On? Get Expert Diagnostics Today
Don't let a check engine light turn into expensive repairs. Our ASE certified technicians can quickly diagnose the problem and provide honest recommendations.
Why Choose Rohnert Park Transmission?
- • Same-day diagnostic appointments available
- • Professional-grade diagnostic equipment
- • ASE certified technicians
- • Honest, upfront recommendations
- • Family-owned since 1997
Mon-Thu: 7:30am-5pm | Fri: 7am-4pm
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