P2142 — Exhaust Gas Recirculation Throttle Control Circuit “A” High #

The wording of this code may differ depending on the vehicle manufacturer. Here are some known label variations for DTC P2142:

• Ford: EGR Throttle Control Circuit “A” High
• GM/Chevrolet: Exhaust Gas Recirculation Throttle Actuator Control Circuit High Voltage
• Dodge/Chrysler: EGR Throttle Control Circuit “A” High Input
• Mercedes-Benz: EGR Throttle Control Circuit High

Summary of Code P2142 #

Diagnostic Trouble Code (DTC) P2142 signals that your vehicle’s engine control module (ECM) has detected an abnormally high voltage in the “A” circuit of the Exhaust Gas Recirculation (EGR) Throttle Control. The EGR system helps reduce nitrogen oxide emissions by recirculating a portion of exhaust gases back into the intake manifold, thus lowering combustion temperatures. The throttle control, in this context, refers to a valve or actuator that precisely regulates how much exhaust gas is recirculated. When the ECM senses a circuit voltage higher than the expected range, it triggers this code. While this issue is often electrical in nature, it can impact drivability and emissions, making prompt diagnosis important.

Common Symptoms for Code P2142 #

When P2142 is stored, you might notice a blend of performance and emissions-related symptoms. Sometimes, the effects can be subtle, but more often than not, they will catch your attention during daily driving. Typical signs include:

• Check Engine Light (CEL) illuminated
• Rough idle or engine hesitation
• Reduced engine power, especially under load
• Increased fuel consumption
• Possible engine knocking or pinging sounds
• Failed emissions test

Probable Causes for Code P2142 #

This DTC is usually the result of an electrical anomaly, but mechanical issues can also play a role. Here are the most common causes, ranked by likelihood:

1. Faulty EGR throttle control actuator or valve (common for wear or internal short circuits)
2. Damaged wiring or connectors in the EGR throttle control “A” circuit (e.g., frayed wires, corrosion, loose pins)
3. Short to voltage within the EGR throttle control circuit (e.g., wire rubbing against a power source)
4. Failed ECM (rare, but possible if all else checks out)
5. Aftermarket modifications interfering with circuit voltage or grounding

Step-by-Step Diagnosis for Code P2142 #

Diagnosing P2142 requires a methodical approach, focusing on both the electrical and mechanical aspects of the EGR throttle control system. Here’s how a professional would tackle the issue:

• 1. Verify the code — Use a professional-grade scan tool to confirm P2142 is present and to check for any related codes.
• 2. Inspect wiring and connectors — Visually examine the EGR throttle control wiring harness and connectors for damage, corrosion, or loose connections.
• 3. Test actuator/valve resistance — Disconnect the EGR throttle control actuator and use a digital multimeter to check for proper resistance and absence of short circuits.
• 4. Check for voltage at the circuit — With the ignition on, use a multimeter to verify that the proper reference voltage is present at the actuator connector.
• 5. Wiggle test — With the system powered, gently move the wiring harness to see if the code resets, indicating an intermittent wiring fault.
• 6. Check ECM outputs — If all else checks out, test for proper ECM operation and output signals. Substitute with a known good ECM if necessary (rarely needed).

Possible Repairs for Code P2142 #

Once you’ve pinpointed the cause, the appropriate repair will depend on the faulty component or wiring. Remedies typically include:

• Repair or replace damaged wiring/connectors in the EGR throttle control circuit
• Replace the EGR throttle control actuator/valve if it fails resistance or function tests
• Secure and protect wiring to prevent future chafing or shorting
• Replace the ECM only if proven faulty after all other possibilities have been exhausted
• Revert aftermarket modifications that may interfere with the circuit

Can You Drive with Code P2142? #

Limited — Not Recommended for Extended Driving. While your vehicle may still operate with this code present, continued driving could lead to increased emissions, decreased performance, or even engine damage in the long run. EGR system faults can also cause your vehicle to fail inspection or emissions testing. Prompt diagnosis and repair are highly advised to avoid further complications.

Vehicles Most Commonly Affected by Code P2142 #

This code can be found across a wide range of makes and models, but is most frequently reported in vehicles equipped with electronically controlled EGR systems. Some commonly affected brands include:

• Ford (F-Series trucks, Focus, Escape)
• GM/Chevrolet (Silverado, Malibu, Cruze)
• Dodge/Chrysler (Ram, Grand Caravan)
• Mercedes-Benz (Sprinter, C-Class)
• Volkswagen (Golf, Passat, Jetta with diesel engines)

Common Mistakes & Best Practices for Code P2142 #

Even experienced technicians can fall into a few traps when dealing with P2142. Keep these best practices in mind:

• Don’t replace the EGR actuator without first inspecting wiring and connectors. Electrical issues are often to blame.
• Always clear the code and retest after repairs to ensure the problem is resolved.
• Use OEM parts whenever possible to avoid compatibility issues.
• Don’t overlook intermittent faults caused by vibration or heat — try a wiggle test during diagnosis.
• Document all steps and findings in case further troubleshooting is needed.

Express FAQ — P2142 #

Here are quick answers to some of the most common questions about DTC P2142:

• Q: Will clearing the code fix the problem?
  A: Clearing the code alone will not resolve the underlying issue. The code will return unless the root cause is corrected.
• Q: Can a bad battery or alternator cause P2142?
  A: While rare, severe electrical system issues can sometimes affect control circuits. Always start diagnosis with the EGR system itself.