P2142 – Exhaust Gas Recirculation Throttle Control Circuit High

P2142 is a powertrain diagnostic trouble code that points to an abnormal electrical condition in an engine fuel injector power/supply circuit that the Engine Control Module (ECM) or Powertrain Control Module (PCM) monitors. Under SAE J2012 formatting, the code structure is standardized, but the exact “injector group” or the specific circuit path being monitored can vary by make, model, and year. Your job is to confirm which circuit the module is calling out by testing power feed, grounds, and control-signal integrity at the injector harness and related power distribution.

What Does P2142 Mean?

Using SAE J2012 code formatting, P2142 indicates a fuel injector group supply circuit fault (an electrical circuit-level issue the controller detects while commanding or monitoring injector operation). SAE J2012 defines the DTC structure and publishes many standardized descriptions in the SAE J2012-DA digital annex; however, the exact component mapping (which injectors are in “Group A/B,” what the feed source is, and how it’s monitored) can vary by vehicle, so you must verify the affected circuit with wiring diagrams and basic electrical testing.

This code is shown without a hyphen suffix, meaning no Failure Type Byte (FTB) is provided here. If an FTB were present (for example, a “-xx” suffix), it would further specify the failure subtype (such as signal state or circuit behavior) while the base code would still describe the same injector supply-circuit monitoring problem. What makes P2142 distinct is that it targets the injector supply/power side as a grouped circuit fault, not a single-cylinder misfire or a generic performance complaint.

Quick Reference

• Code type: Powertrain (P-code), fuel injection electrical circuit monitoring
• What it indicates: Abnormal condition detected in an injector group supply circuit (definition details can vary by vehicle)
• Most likely systems involved: Injector power feed, injector harness, power distribution (fuses/relay), ECM/PCM driver monitoring
• Typical immediate effects: Rough running, reduced power, hard start/no-start depending on how many injectors lose proper supply
• What to confirm first: Battery voltage at injector feed under load, fuse/relay integrity, voltage drop on power and ground paths
• Best first test: Back-probe injector feed and verify stable B+ during cranking/idle while wiggling harness

Real-World Example / Field Notes

In the bay, P2142 often shows up after other work disturbed the injector harness: intake manifold service, valve cover work, or rodent damage repair. One common pattern is an engine that starts and immediately runs rough, then smooths out when you touch or reposition the harness—pointing you toward a marginal connection rather than a “bad injector.” Another pattern is an intermittent stumble over bumps with a clean-looking connector, where a voltage-drop test under load reveals a weak fuse contact or relay terminal feeding the injector supply. On some vehicles, the “injector group supply” is monitored through a shared power feed or internal current-sense strategy, so a single corroded splice, loose terminal, or chafed section can trigger the code even when individual injector resistance checks look normal.

Symptoms of P2142

• Check engine light illuminated (MIL) and code stored as a current or pending fault.
• Reduced power or limp-in behavior if the Powertrain Control Module (PCM) limits torque due to an implausible signal relationship.
• Rough running such as misfire-like feel, stumble, or uneven acceleration when the PCM can’t trust a key input.
• Hard starting or extended crank if fueling/airflow decisions are affected by a correlation concern.
• Poor fuel economy from fallback strategies that substitute default values for a suspect input.
• Intermittent symptom that comes and goes with vibration, heat soak, or moisture intrusion affecting wiring integrity.
• Transmission shift oddities on some vehicles when the PCM shares implausible torque/load data with the Transmission Control Module (TCM).

Common Causes of P2142

Most Common Causes

• Connector or harness issue causing a powertrain sensor or actuator circuit signal to become implausible versus another reference signal (fretting, spread terminals, corrosion, water intrusion).
• Shared 5-volt reference problem (short-to-ground, short-to-voltage, or excessive load) affecting multiple sensors and creating correlation faults.
• High resistance in a sensor ground (poor splice, loose ground eyelet, damaged ground wire) skewing multiple signal readings.
• Intermittent open/short in a signal circuit near hot components or moving points (engine cover rub-through, bracket chafe).
• A sensor commonly associated with correlation monitoring on your platform reading out of plausibility due to contamination, mechanical issue, or internal drift.

Less Common Causes

• Charging system over/under-voltage events that destabilize sensor reference and module inputs (verify alternator output under load).
• Aftermarket wiring modifications (remote start, alarm, audio) introducing noise, poor splices, or backfeeding into power/ground circuits.
• Mechanical timing/airflow issues that make otherwise good sensors disagree (vacuum leaks, restricted intake/exhaust, sticking throttle/air metering faults), confirmed only by plausibility tests.
• Control module issue such as a possible internal processing or input-stage issue, considered only after external wiring, powers/grounds, and signals test good.
• Rare network integrity problem where a required signal is delivered over the Controller Area Network (CAN) and arrives corrupted or missing, verified by network checks.

Diagnosis: Step-by-Step Guide

Tools you’ll want: a scan tool with live data and freeze-frame, a digital multimeter (DMM), back-probe pins or piercing probes, wiring diagram access for your exact vehicle, a battery/charging system tester, an oscilloscope (helpful for intermittent dropouts/noise), a smoke machine (for air leaks when applicable), and basic hand tools for connector inspection.

1. Confirm the complaint and record freeze-frame data (RPM, load, voltage). Clear the code and see if it returns on a short road test to verify it’s active.
2. Check battery condition and charging voltage. A stable 12.6V key-off (typical) and ~13.5–14.8V running (typical) helps rule out voltage-driven plausibility errors.
3. With the scan tool, monitor key live data PIDs involved in plausibility/correlation on your platform. Look for an obvious outlier (one signal stuck, flatlined, or jumping) while others behave normally.
4. Do a visual inspection of harness routing and connectors for commonly associated circuits: look for oil intrusion, coolant contamination, bent pins, loose locks, and chafing near brackets or heat sources.
5. Key on, engine off: measure the 5V reference at the affected sensor(s). If it’s low/high or unstable, unplug sensors on the shared 5V line one at a time to see when the reference returns to normal.
6. Verify sensor ground integrity with a voltage drop test: load the circuit (engine running if appropriate) and measure ground drop from sensor ground to battery negative. Excessive drop indicates resistance in the ground path.
7. Check the suspect signal circuit for shorts to ground/voltage and for opens using DMM resistance checks (with modules disconnected as required by your service info). Wiggle the harness while observing for intermittent change.
8. If available, use an oscilloscope to look for noise, dropouts, or clipping on the signal and 5V reference during the conditions that set the code (snap throttle, heat soak, vibration).
9. Run a plausibility check: compare the suspect signal to a known-good reference in live data (for example, commanded vs actual, or two measurements that should track). If they diverge beyond a rational range, focus on the circuit that disagrees.
10. After repairs, clear codes and complete a drive cycle similar to the freeze-frame conditions. Confirm the monitor runs and P2142 does not reset.

Professional tip: If P2142 is intermittent, don’t replace parts based on a single snapshot—use freeze-frame to recreate the exact load/temperature conditions, then do voltage drop and scope checks while wiggling the harness; correlation faults are often caused by a brief reference/ground disturbance that a DMM alone can miss.

Possible Fixes & Repair Costs

Fix cost depends on what your testing proves. Expect low cost ($0–$80) when the issue is found during inspection: repairing a rubbed-through harness section, cleaning/retensioning a connector, fixing a loose ground, or correcting a blown fuse/relay feed you verified with a voltage-drop test. A typical repair ($120–$450) is justified when you measure an injector circuit control or power feed problem that traces to damaged wiring, poor terminal tension, or high resistance at a splice, and you confirm the fix by restoring proper voltage, continuity, and signal behavior under load.

High cost ($450–$1,800+) usually applies when testing supports replacement of a commonly associated component such as a fuel injector (for example, resistance out of spec compared to other cylinders, current ramp abnormal, or the circuit pulls the driver down), or when you’ve proven all external power, ground, and circuit integrity are good and you’re left with a possible internal processing or input-stage issue in the Engine Control Module (ECM) or Powertrain Control Module (PCM). Labor can rise if access is difficult, the harness is buried, or you must perform extended wiggle testing and heat/soak verification to reproduce an intermittent.

Can I Still Drive With P2142?

Sometimes you can limp the vehicle, but it’s not a “drive it like normal” code. A fuel injector circuit plausibility fault can cause a misfire, rough running, reduced power, and catalytic converter overheating if fueling is inconsistent. If you feel strong shaking, the Check Engine light is flashing, or the engine is stalling, stop driving and have it towed to prevent exhaust and engine damage. If it runs smoothly, drive only as needed to reach a shop while avoiding heavy throttle and long high-speed trips.

What Happens If You Ignore P2142?

Ignoring P2142 can turn an intermittent circuit issue into a repeat no-start or a sustained misfire, and it can overheat and damage the catalytic converter if unburned fuel reaches the exhaust. A worsening connection can also stress the injector driver circuitry and create more extensive wiring repairs later.

Last updated: February 13, 2026

Vehicles Commonly Affected by P2142

P2142 is commonly seen on vehicles with tightly packaged engine bays and complex injector wiring looms, where heat and vibration can stress connectors and harness routing. It’s often reported across several manufacturers, including Ford, Volkswagen/Audi, GM, and some diesel applications, because the underlying architecture (multiple injectors, shared power feeds, and ECM/PCM low-side drivers) makes these circuits sensitive to small resistance changes. The exact circuit the code references still depends on the year and calibration, so confirm with scan data and basic electrical testing.