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DTC codes / Jaguar codes / P1607

P1607 · JaguarMIL Output Circuit

P1607 on a Jaguar means the engine control module (ECM) has detected a fault in the circuit that drives the malfunction indicator lamp (MIL), commonly called the check engine light. The ECM monitors the voltage on the MIL output circuit and sets this code when the expected voltage is not present, either because the circuit is open, shorted, or the bulb or LED driver has failed.

SystemPowertrain
Code typeJaguar specific
SeverityMedium
Fix difficultyIntermediate
AreaComputer and output circuits

Symptoms you may notice

  • The check engine light does not illuminate when the ignition is switched on, so the bulb check fails.
  • The check engine light stays on continuously even when no other fault codes are stored.
  • The check engine light may flicker or behave erratically while driving over bumps.
  • Other stored codes may be present but the driver cannot see the warning light to know a fault exists.
  • Often no symptoms besides the warning light itself, because the MIL circuit does not affect engine performance.

Common causes, most likely first

  1. Failed instrument cluster bulb or light-emitting diode (LED) for the check engine light.
  2. Open circuit in the wire between the ECM and the instrument cluster, often due to a broken wire or poor connector pin tension.
  3. Short to ground or short to voltage on the MIL output wire, frequently caused by chafing against a metal bracket.
  4. Corroded or water-damaged connector at the ECM or at the back of the instrument cluster.
  5. Internal driver failure inside the ECM, which is less common but possible after a voltage spike or jump-start.
  6. Aftermarket alarm or remote start wiring tapped into the MIL circuit incorrectly.

How to diagnose and fix it

  1. Verify the check engine light bulb or LED by switching the ignition on and watching for the bulb check; replace the bulb if it does not flash briefly.
  2. Check the instrument cluster connector and the ECM connector for corrosion, loose pins, or water intrusion, and clean or reseat as needed.
  3. Disconnect the battery and use a multimeter to check continuity and resistance on the MIL output wire between the ECM and the cluster, looking for an open circuit.
  4. With the ignition on, measure voltage on the MIL output wire at the cluster to confirm whether the ECM is commanding the light on and off correctly.
  5. Inspect the wiring harness along its routing for chafing, pinches, or heat damage, especially near the bulkhead and under the dashboard.
  6. If the circuit and bulb are good but the ECM does not pull the wire low when commanded, substitute a known-good ECM or perform a driver test with a scan tool before condemning the module.
  7. Clear the code and perform a road test with several ignition cycles to confirm the MIL circuit operates correctly and the code does not return.

Why the check engine light stays dark

  • A failed instrument cluster voltage regulator or a bad ground at the cluster can mimic a MIL circuit fault, so always check cluster power and ground before replacing the ECM.
  • Some Jaguar models use a smart junction box or body control module to pass the MIL signal, and a fault in that module can set P1607 even when the ECM and bulb are fine.
  • Aftermarket radio or alarm installers often probe the wrong wire behind the dash and damage the MIL circuit, so look for non-factory splices before assuming a component failure.
  • The ECM may set P1607 intermittently if the MIL wire is routed too close to an ignition coil or injector harness, causing induced voltage spikes that confuse the driver circuit.
  • Do not replace the ECM based on P1607 alone; confirm the driver actually fails to pull the circuit low with a lab scope or a known-good test lamp.

Can I keep driving with P1607?

You can usually continue driving because the MIL circuit fault does not affect engine operation, but you will not see the check engine light if another fault develops. Avoid ignoring the code, and have the circuit inspected soon so that future emissions or engine problems are not hidden.

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 Jaguar vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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