01 How to Fix an Alternator that is Draining a Car Battery • 02 How Cars Can Now Detect Driver Fatigue • 03 Why Won't My Car Accelerate But the RPMs Goes Up? • 04 What Happens When Car Safety Systems Fail • 05 This Is Why Your Car’s Battery Terminals Are Corroded • 06 Engineers Reveal Why Most Car Doors Are Designed To Rip Apa… • 07 P0010 A Camshaft Position Actuator Circuit (Bank 1) • 08 Is the Land Rover Defender 2022 Worth a Trial? • 09 What Is Blow-By & How to Prevent It From Harming Your Engine • 10 That Rotten Egg Smell From Your Exhaust Isn't Normal: Here'… •

DTC codes / Chrysler codes / P1418

P1418 · ChryslerSecondary Air Injection System Relay A Control Circuit High

P1418 on Chrysler vehicles means the powertrain control module (PCM) has detected a high voltage condition on the control circuit for the secondary air injection (AIR) system relay, specifically relay A. The PCM expects to see a low-voltage signal when commanding the relay on, but the circuit is showing voltage that is too high, indicating an open circuit, a short to voltage, or a faulty relay.

SystemPowertrain
Code typeChrysler specific
SeverityLow
Fix difficultyIntermediate
AreaAuxiliary emission controls

Symptoms you may notice

  • Illumination of the check engine light (malfunction indicator lamp) on the dashboard.
  • Often no symptoms besides the warning light, as the secondary air injection system only operates during cold starts.
  • Slight increase in tailpipe emissions during the first few minutes after a cold start.
  • In some cases, a rough idle or stumble immediately after starting when the engine is cold.
  • Rarely, a noticeable delay in the AIR pump engaging or a lack of the typical whirring sound on cold start.

Common causes, most likely first

  1. Open circuit in the control wire between the PCM and the AIR relay A, such as a broken wire or corroded connector.
  2. Short to voltage on the control circuit, often due to chafed wiring contacting a power source.
  3. Failed AIR relay A, where the coil is open or the internal contacts have failed.
  4. Corroded or damaged PCM connector pins at the relay control circuit terminal.
  5. Faulty PCM driver for the AIR relay circuit, though this is less common.
  6. Blown fuse or poor ground connection for the relay coil, indirectly affecting circuit voltage.
  7. Aftermarket accessories or remote start wiring that backfeed voltage into the control circuit.

How to diagnose and fix it

  1. Verify the code with a scan tool and check for any related codes in the AIR system before proceeding.
  2. Inspect the AIR relay A and its socket for corrosion, loose pins, or signs of overheating; swap the relay with a known-good identical relay to see if the code changes.
  3. Disconnect the PCM connector and the relay, then measure resistance on the control wire between them to check for an open circuit; repair any broken wire or high resistance.
  4. With the relay removed and ignition on, measure voltage on the control circuit at the relay socket to check for a short to voltage; trace and repair any chafed wire.
  5. Check the relay ground circuit for integrity, including the ground point and wire condition, and repair as needed.
  6. If all wiring and the relay test good, perform a bidirectional test with a scan tool to command the AIR relay on and off while monitoring the control circuit voltage; if the PCM does not respond correctly, suspect the PCM.
  7. Clear the code and perform a cold-start drive cycle to verify the repair, ensuring the AIR system activates and no pending codes return.

Relay A Circuit High Voltage Traps

  • A common mistake is replacing the AIR pump when the code actually points to the relay control circuit; the pump may be fine and the relay simply not receiving a proper ground or control signal.
  • The PCM expects to see a low voltage on the control circuit when the relay is commanded on; a high voltage reading often means the control wire is shorted to battery voltage somewhere along its path, not that the relay itself has failed.
  • Corrosion inside the relay socket can create enough resistance to set a high voltage code without any visible damage to the relay or wiring, so always inspect the socket terminals closely.
  • Aftermarket remote start or alarm systems that tap into the AIR relay circuit can backfeed voltage and trigger P1418, especially if the installation was not properly diode-isolated.
  • On some Chrysler models, the AIR relay is part of the integrated power module (IPM), and a fault in the IPM internal circuitry can mimic a wiring problem, so module testing may be necessary after all external checks pass.

Can I keep driving with P1418?

You can generally continue driving with P1418 because the secondary air injection system only affects emissions during cold starts and does not impact engine performance or safety. However, avoid long-term neglect, as the fault may cause slightly higher emissions and could lead to other AIR system codes or a failed emissions test.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage