Ram Cummins · Injector Circuit Cylinder 2High

Ram Cummins P0202: Injector Circuit Open — Cylinder 2

P-Code 0202 (FMI N/A) — Injector Circuit Open — Cylinder 2

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Quick Answer

P0202 on the Ram Cummins means the ECM cannot detect current flow through the cylinder 2 injector circuit. Check the valve cover harness and connector before replacing the injector.

Overview: Ram Cummins P-Code 0202

P0202 on the Ram Cummins is a hard open circuit fault on the cylinder 2 fuel injector driver. ProfessionalDieselRepair.com always inspects the valve cover harness pass-through before condemning the injector — a broken wire inside the harness bundle at the cover grommet is a common cause and a far cheaper fix than a new injector.

Repair Snapshot

Time

1.5 - 4 Hours

Difficulty

Advanced

Parts Cost

$200 - $600

Dealer Labor

$400 - $900

Tools Required

  • Cummins INSITE
  • Diesel Laptops Scan Tool
  • Multimeter
  • Injector Removal Tool
  • Torque Wrench

What P-Code 0202 Means

P0202 on the Ram Cummins (ISB 5.9L and 6.7L) means an open circuit has been detected in the fuel injector driver circuit for cylinder 2. The ECM commands the injector solenoid but receives no return signal or current flow, indicating the circuit is broken. ProfessionalDieselRepair.com addresses P0202 by first testing the injector harness and connector before condemning the injector — open circuits on Ram Cummins trucks frequently trace to a broken solenoid wire at the valve cover pass-through.

Symptoms Drivers Notice

  • Check engine light on
  • Single-cylinder misfire at idle or under load
  • Rough running with vibration at idle
  • Possible white smoke from incomplete combustion on cylinder 2
  • Reduced power and fuel efficiency

Most Likely Root Causes

Broken or open wire in the injector harness at the valve cover pass-through

Very Common

Heat cycling and vibration stress the wiring at the valve cover grommet, causing individual solenoid wires to fracture inside the insulation and produce an open circuit reading.

Corroded or damaged injector solenoid connector

Moderate

Oil and moisture intrusion at the cylinder 2 injector connector cause pin corrosion that increases circuit resistance to an open state detected by the ECM.

Failed injector solenoid winding

Moderate

The injector solenoid winding can fail internally due to heat or mechanical damage, producing an open-circuit resistance reading that cannot be repaired without injector replacement.

ECM injector driver circuit fault

Rare

In rare cases the ECM's internal driver for cylinder 2 fails, producing a false open-circuit fault. Confirm by swapping a known-good injector to the cylinder 2 position and checking whether the fault follows the injector or the ECM channel.

Common Misdiagnoses (Don't Waste Parts)

Parts-cannon injector replacement without harness and connector testing first

Why it happens: P0202 names the injector circuit, and a high-resistance or open solenoid reading seems to confirm injector failure without investigating whether the fault is in the harness.

Do this instead: Measure solenoid resistance directly at the injector body rather than at the harness connector. If resistance is normal at the injector but open at the connector, the fault is in the wiring.

Assuming a cylinder 2 misfire is always the injector rather than a compression or valve issue

Why it happens: P0202 makes the injector circuit the obvious suspect; underlying mechanical issues affecting cylinder 2 go undiagnosed.

Do this instead: Perform a cylinder cut-out test in Cummins INSITE to confirm cylinder 2 is non-contributing, then check injector circuit resistance and harness integrity before attributing the misfire solely to the injector.

Master Tech Commentary

Mechanic's Notes

Shop tip: ProfessionalDieselRepair.com inspects the valve cover pass-through on every Ram Cummins P0202 call before pulling the injector. The wiring grommet at the valve cover is a high-wear point — a broken wire or cracked insulation inside the harness bundle produces a clean open-circuit reading that looks exactly like a failed injector solenoid. Run the injector cut-out test in Cummins INSITE first to confirm cylinder 2 is non-contributing, then measure solenoid resistance at the connector. A good resistance reading with a confirmed non-contribution means the open is in the harness, not the injector.

Step-by-Step Diagnostic Procedure

  1. Step 1: Connect Cummins INSITE or Diesel Laptops and confirm P0202 is stored. Note if companion misfire codes or cylinder balance faults are present — a balance fault on cylinder 2 alongside P0202 confirms cylinder 2 is not contributing.
  2. Step 2: Perform an injector cut-out test using Cummins INSITE. Disable each injector in turn and monitor RPM drop. If disabling cylinder 2 produces no RPM change while all other cylinders produce a clear drop, the injector is confirmed as non-contributing.
  3. Step 3: Inspect the injector harness connector at the valve cover for damage, corrosion, or broken wires. On the ISB 6.7L, the pass-through grommet at the valve cover is a known failure point where solenoid wires can chafe and break.
  4. Step 4: Use a multimeter to check injector solenoid resistance at the cylinder 2 connector — ISB solenoids typically read 0.4–0.9 ohms. An OL (open) reading confirms solenoid or wiring failure; a short to ground reading suggests an internal solenoid short.
  5. Step 5: If harness and connector check out but the injector is confirmed non-contributing with good solenoid resistance, the injector may have an internal mechanical failure requiring replacement.

Live Data & Freeze-Frame Tips

Use the injector cylinder cut-out function in Cummins INSITE to disable cylinder 2 and monitor RPM drop. Compare the drop from cylinder 2 against all other cylinders — a cylinder producing no RPM change when cut out is confirmed non-contributing. Also monitor injector pulse width on cylinder 2 with Diesel Laptops: a cylinder receiving no commanded pulse confirms the ECM has disabled that driver due to the open-circuit fault.

Safety Warnings

  • Always clean the area around the injector before removal to prevent debris from entering the cylinder head.
  • Injectors on the ISB are under significant spring force — follow the manufacturer torque sequence and use proper injector hold-down hardware.

When to Limp In vs Tow

P0202 with an active misfire on cylinder 2 means the engine is running on five cylinders. Extended operation in this state can wash cylinder walls with unburned fuel, accelerating wear. Have the truck repaired promptly and avoid extended high-load operation with the fault active.

Prevention Tips for Fleets & Owner-Operators

  • Inspect the valve cover injector harness pass-through for cracked insulation during valve cover gasket replacement.
  • Use OEM-quality or Cummins-approved injectors when replacement is necessary to ensure proper solenoid resistance characteristics.
  • Address any fuel contamination or aeration issues promptly to protect injector solenoid windings.

Related Fault Codes

P0201

Injector circuit open — cylinder 1; multiple injector open codes suggest a common wiring or power supply fault.

P0203

Injector circuit open — cylinder 3.

P0300

Random/multiple cylinder misfire — may accompany P0202 if the non-contributing cylinder causes overall combustion instability.

Frequently Asked Questions

What does P0202 mean on a Ram Cummins?

P0202 means the ECM has detected an open circuit in the fuel injector driver for cylinder 2. The ECM commands the injector but receives no current flow in return, meaning the electrical path from the ECM through the solenoid and back is broken somewhere.

Where should I check first for a P0202 open circuit?

Start at the valve cover pass-through grommet where the injector harness exits the cylinder head area. Heat and vibration frequently break individual solenoid wires inside the bundle at this point, producing an open-circuit fault without visible external damage.

How do I test the injector solenoid on cylinder 2?

Unplug the cylinder 2 injector connector and measure resistance across the solenoid terminals with a multimeter. ISB solenoids should read 0.4–0.9 ohms. An open-loop (OL) reading confirms solenoid or wiring failure. Also check for a short to ground on either terminal.

Will P0202 clear itself after the injector is replaced?

No — P0202 must be cleared with a scan tool. Use Cummins INSITE or Diesel Laptops to clear the fault after repair and perform a test drive to confirm the code does not return and cylinder balance is restored.

Can I drive my Ram with P0202 active?

Short-distance low-speed driving to a shop is feasible, but extended operation with a non-contributing cylinder can wash the cylinder wall with unburned fuel and accelerate engine wear. Address P0202 promptly.

How much does it cost to fix P0202 on the Ram Cummins?

A harness repair or connector replacement is typically under $100 in parts. If the injector itself needs replacement, ISB injectors range from $200–$600, with 1.5–4 hours of labor depending on accessibility and whether the valve cover must be removed.