2020 Corvette Throttle Body Plug Problems? Here's How to Fix It

How to Fix a Throttle Body Issue

Experiencing throttle body issues with your 2020 Chevrolet Corvette can be frustrating. Many owners have encountered symptoms ranging from idle problems to indicator lights. As one owner shared: "This is pissing me off I am getting closer and closer to converting the car to a cable throttle body. So after talking to Mike @ Soler Performance and giving him the full run down and history of what has worked in the past and what has changed to potentially cause these problems." (source This guide will walk you through diagnosing and resolving common throttle body issues based on experiences from other 2020 Chevrolet Corvette owners.

Symptoms

Throttle body issues can manifest in several ways on your truck. A common symptom is an unstable or erratic idle. This can involve the engine idling too high or too low, or even fluctuating up and down. You might notice this especially when the vehicle is stopped or in park.

Another symptom reported by owners is the presence of smoke. While not always directly linked to the throttle body itself, smoke can indicate a larger engine issue that may be exacerbated by a malfunctioning throttle body. Keep an eye on the color and smell of the smoke, as this can provide clues to the underlying cause.

Soot buildup is another indicator that your throttle body might be having issues. A dirty throttle body can restrict airflow and cause incomplete combustion, leading to excessive soot deposits in the intake manifold and around the throttle plate. This soot can further degrade performance and worsen idle problems.

Finally, keep an eye out for the indicator light on your dashboard. This light can illuminate for a variety of reasons, but a faulty throttle body or related sensor can trigger it. Getting the code read at an auto parts store or mechanic shop can help you pinpoint the exact problem.

Most Likely Cause

Based on owner reports, a primary cause of throttle body issues in the 2020 Chevrolet Corvette relates to a faulty or improperly connected plug in the throttle body wiring harness. Specifically, issues with the plug can cause intermittent connectivity, leading to the REP (Reduced Engine Power) mode activation that several owners have experienced. This can stem from corroded connections, damaged wiring, or even a poorly manufactured plug.

"Probably got around 800 miles on it since building the new throttle body wire harness without incident. I am about 97% confident that the car is fixed of REP," one owner mentioned (source. This suggests that ensuring a solid, reliable connection at the plug is crucial for proper throttle body function. This issue could be exacerabted by engine movement, temperature changes, and general wear and tear over time.

How to Diagnose

Diagnosing a faulty throttle body plug involves a methodical approach.

1. Visual Inspection: Begin by visually inspecting the throttle body wiring harness and plug. Look for any signs of damage, such as frayed wires, cracked insulation, or corroded connectors. Pay close attention to the pins inside the plug to ensure they are straight and free of corrosion.
2. Connectivity Check: Use a multimeter to check the continuity of the wires in the harness. Disconnect the plug from the throttle body and the engine control unit (ECU). Set the multimeter to the continuity setting and test each wire individually.
3. Voltage Check: With the ignition on, use a multimeter to check for proper voltage at the throttle body plug. Consult the vehicle's service manual for the correct voltage readings.
4. Scan for Codes: Use an OBD-II scanner to check for any diagnostic trouble codes (DTCs) related to the throttle body or its sensors. Common codes include P0120 (Throttle/Pedal Position Sensor/Switch A Circuit Malfunction) and P0121 (Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem).
5. Wiring Harness Flex Test: While monitoring the OBD-II scanner for changes in throttle position sensor readings, gently flex and wiggle the throttle body wiring harness. If the readings fluctuate or become erratic, it indicates a wiring issue.
6. Throttle Body Cleaning: As one owner stated "my 97 hit the limp mode at an intersection in town and i called my friend that knows the ls. he said to clean the throttle body behind the blade because thats where it cakes up with grime. it worked and has been a year since. just a thought" (source. Use a throttle body cleaner to clean the assembly thoroughly.

Tools required:

• OBD-II scanner
• Multimeter
• Throttle body cleaner
• Basic hand tools (screwdrivers, pliers, etc.)

Step-by-Step Fix

Addressing a faulty throttle body plug involves replacing or repairing the wiring harness and plug. Here's a step-by-step guide:

1. Disconnect the Battery: Disconnect the negative terminal of the battery to prevent electrical shorts.
2. Locate the Throttle Body Plug: Find the throttle body plug on the intake manifold. It is usually a multi-pin connector with several wires leading to it.
3. Remove the Old Plug: Disconnect the old plug from the throttle body. Use a small screwdriver or pick to release any locking tabs.
4. Inspect the Wiring Harness: Examine the wiring harness for any signs of damage, such as frayed wires or cracked insulation. If the harness is damaged, you may need to replace the entire harness.
5. Replace the Plug: If the plug is the only damaged part, you can replace it with a new one. Splice the wires from the old harness to the new plug, ensuring that you match the wire colors and positions. Use butt connectors or solder to create a secure connection.
6. Clean the Throttle Body: While you have the throttle body disconnected, clean it with a throttle body cleaner. Remove any carbon buildup or debris from the throttle plate and bore.
7. Reconnect the Plug: Reconnect the new plug to the throttle body. Make sure it clicks into place and is securely fastened.
8. Reconnect the Battery: Reconnect the negative terminal of the battery.
9. Clear Diagnostic Trouble Codes: Use an OBD-II scanner to clear any diagnostic trouble codes (DTCs) related to the throttle body.
10. Test the Vehicle: Start the vehicle and let it idle for a few minutes. Check for any signs of problems, such as rough idling or stalling. Take the vehicle for a test drive to ensure that the throttle response is smooth and consistent.

Parts and Tools Needed

• Throttle body plug (part number varies depending on the specific vehicle)
• Wiring harness (if necessary)
• Butt connectors or solder
• Wire stripper/crimper
• Throttle body cleaner
• OBD-II scanner
• Basic hand tools (screwdrivers, pliers, etc.)

An alternative mentioned by an owner is an LS3 throttle body. "So there is a dude on fleabay that apparently got like a semi truck load of LS3 new OEM gold blade throttle bodies and has been selling them for 145 bucks free shipping," (source but be aware of potential tuning needs if you swap out the throttle body.

Real Owner Costs

The cost of repairing a throttle body issue can vary depending on the cause and the extent of the damage. Here are some examples based on real owner experiences:

• DIY Repair (Plug Replacement): Replacing the throttle body plug yourself can cost as little as $20-$50 for the plug and connectors, plus a few hours of your time.
• Professional Repair (Plug Replacement): Having a mechanic replace the plug can cost between $100 and $200, including parts and labor.
• Professional Repair (Throttle Body Replacement): Replacing the entire throttle body can cost between $300 and $600, including parts and labor.

One owner reported finding new OEM throttle bodies for $145, indicating that you might be able to find a good deal if you shop around. However, always ensure that the part is compatible with your vehicle before purchasing.

Prevention

Preventing throttle body issues involves regular maintenance and careful attention to detail. Here are some tips:

• Keep the Throttle Body Clean: Regularly clean the throttle body with a throttle body cleaner to prevent carbon buildup and ensure smooth operation.
• Inspect the Wiring Harness: Periodically inspect the throttle body wiring harness for any signs of damage, such as frayed wires or cracked insulation. Replace the harness if necessary.
• Ensure Proper Connections: Make sure that all connections to the throttle body are clean and secure. Use dielectric grease to protect the connectors from corrosion.
• Address Issues Promptly: If you notice any symptoms of throttle body issues, such as rough idling or stalling, address them promptly. Ignoring the problem can lead to more serious damage.

What Owners Say

Real experiences from CHEVROLET owners:

Success Stories

"This is pissing me off I am getting closer and closer to converting the car to a cable throttle body. So after talking to Mike @ Soler Performance and giving him the full run down and history of what has worked in the past and what has changed to potentially cause these problems." — Mr. Black (source)

"Yeah, I should have mentioned that I also have an LS2 throttle body, and that made things worse too. Two tuners have worked on my car, one just sucked at return-to-idle and the other did a tolerable job of it, but with a lot of surging while coasting to a stop, and it still occasionally stalled." — NSFW (source)

"my 97 hit the limp mode at an intersection in town and i called my friend that knows the ls. he said to clean the throttle body behind the blade because thats where it cakes up with grime. it worked and has been a year since. just a thought" — cdw (source)

Owner Experiences

"The vehicle had a stage 4, 4:10 gear set differential from dynotech engineering that was always a little noisy since I’ve had the vehicle. After a few sets of donuts and hard driving it was screaming!" — C5Zrod_02 (source)

"Probably got around 800 miles on it since building the new throttle body wire harness without incident. I am about 97% confident that the car is fixed of REP." — Mr. Black (source)

"Their was no noise during acceleration or deceleration, just noisy during a steady cruise. I haven’t had much time to mess with the car since we’ve been in the middle of a move so I’ve been driving the car very little at WOT and no throttle for the past few months." — Kubs (source)

Lessons Learned

⚠️ "I still have the factory diff in mine with about 42K miles. When I installed the AMT diff mount I noticed some whine above 45mph when at constant throttle." — Kubs (source)

Real Repair Costs

"Quote: Originally Posted by Mr. Black So there is a dude on fleabay that apparently got like a semi truck load of LS3 new OEM gold blade throttle bodies and has been selling them for 145 bucks free shipping." — Tusc (source)

FAQ

Q: How long does it take to fix a throttle body plug issue?

A: Replacing a throttle body plug can take anywhere from 1 to 3 hours, depending on your experience level. If you are replacing the entire wiring harness, it may take longer.

Q: Can I drive with a faulty throttle body plug?

A: It is not recommended to drive with a faulty throttle body plug. The vehicle may experience reduced power, rough idling, or stalling, which can be dangerous.

Q: Is this a common issue on the 2020 Chevrolet Corvette?

A: While not extremely widespread, throttle body plug issues have been reported by several owners of the 2020 Chevrolet Corvette. Regular maintenance and inspection can help prevent this problem.

Q: DIY vs mechanic - what's recommended?

A: If you are comfortable working on cars and have some experience with electrical repairs, you can likely replace the throttle body plug yourself. However, if you are not comfortable with electrical repairs or are unsure of the proper procedure, it is best to take the vehicle to a qualified mechanic.