Fix P0201: Mechanic’s solutions that WORKED

The code P0201: Injector Circuit/Open – Cylinder 1 points out a fault in the Injector Circuit/Open for Cylinder 1, and most likely is caused by a faulty injector, wiring issue, or a problem with the ECM. Diagnosing this issue involves checking the injector’s resistance, inspecting wiring, and potentially swapping injectors to isolate the problem.

P0201 quick overview

Meaning	P0201: Injector Circuit/Open – Cylinder 1
Is it serious?	This code can be serious as it directly affects the engine’s fuel delivery, potentially leading to misfires, poor performance, and even engine damage if left unaddressed.
Possible causes	– Faulty injector for cylinder 1 – Open or shorted injector wiring for cylinder 1 – Poor electrical connection for injector 1 – Faulty Engine Control Module (ECM)
How to diagnose?	Check Injector Resistance: Measure and compare the resistance of injector 1 with others. Inspect Wiring and Connectors: Examine the wiring and connectors to injector 1 for damage or corrosion. Swap Injectors: Switch injector 1 with another to see if the code follows the injector. Load Test Wiring: Perform a load test on the injector 1 wiring to check for internal damage. Check for ECM Updates: Verify if there’s a software update for the ECM.

How to fix P0201 – learn from mechanics

I looked into P0201 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Volkswagen

Vehicle Information:
2002 Volkswagen Beetle Sport 1.8L

Issue + Repair History:

• Experiencing misfires and setting code P0201.
• Swapped coils and car temporarily ran fine.
• Replaced #1 coil and spark plugs.
• Misfire and Cylinder 1 injector code returned intermittently.

Other OBD2 Codes + Test Results:

• Po201: Cylinder 1 injector
• Po301: Cylinder 1 misfire
• Po300: Random misfire

Suggestions to Fix Issue:

• Inspect injector harness for opens or shorts.
• Swap injectors to see if the problem follows.
• Check the injector and its circuit as the cause of the misfire.
• Investigate possible resistance in the harness affecting the injector.
• Consider a possible software update on the ECM based on relevant TSBs.
• Perform a leak-down test to check for bad exhaust valve seats.
• Measure injector resistance, especially from the ECM connector to identify wiring issues.

Final Fix:

• After the car ran poorly again, testing indicated a misfire on cylinder 1.
• Replaced #1 injector and then the coil again.
• Found a pinched harness on the driver’s side which was repaired.
• No further issues were reported after these fixes.

Case #2: Volkswagen

Vehicle Information:
2004 Volkswagen Jetta TDI 1.9L

Issue + Repair History:

• Running rough with check engine light on.
• Scanned and found code P0201 for injector 1 circuit.
• Checked resistance of injector #1 and compared to others.
• Checked continuity from the main plug at the cylinder head to the ECM.

Other OBD2 Codes + Test Results:

• P0201: Injector 1 circuit

Suggestions to Fix Issue:

• Swap injectors to see if the problem follows, indicating a faulty injector.
• Inspect the cam lobes for wear as it might affect injector performance.
• Check for poor connections at the injector harness plug.
• Consider issues with the wiring harness in the head, which may have poor connections.
• Tighten connections at the injector harness plug and check the readings for the injector.
• Look for a potential service bulletin regarding harness problems.
• Consider the possibility of a partially clogged injector causing the code.

Final Fix:

• The issue was with the injector harness under the valve cover.
• Replaced the injector harness with a new one from VW.
• The vehicle has been running without issues for a week since the replacement.

Case #3: Dodge

Vehicle Information:
2017 Dodge Grand Caravan Crew 3.6L

Issue + Repair History:

• Vehicle experienced intermittent no start and misfires on Cylinder 5.
• Initially had codes P2107, U0426-31, and P0513.
• Replaced #5 injector, coil, and plug after finding it had 1 ohm resistance compared to others at 12 ohms.
• After multiple ECM repairs and replacements, still faced issues.
• Found every injector code open (P0201 – P0206) after further issues.

Other OBD2 Codes + Test Results:

• P0201: Injector circuit open
• P0202: Injector circuit open
• P0203: Injector circuit open
• P0204: Injector circuit open
• P0205: Injector circuit open
• P0206: Injector circuit open
• P2107: ETC Module
• U0426-31: Minikrypt Error
• P0513: SKIM Key

Suggestions to Fix Issue:

• Check for shorts in the wiring that might be affecting the ECM.
• Consider swapping injectors to verify if the issue follows.
• Inspect the injector harness for corrosion or poor connections.
• Look for service bulletins related to injector wiring harnesses.
• Confirm the integrity of the ECM, and consider the quality of the rebuilder if using a rebuilt ECM.
• Examine multi-way connectors for water or corrosion.
• Perform a load test on individual wires for a more accurate diagnosis than an Ohm test.
• Check for any shorts in the injector circuits that might be damaging the ECM.

Final Fix:

• After replacing the shorted injector and all injectors due to a short, the vehicle still had issues.
• Eventually, a new ECM from Chrysler resolved the problem, indicating that the previous ECM repairs were ineffective.
• The rebuilt ECMs from a Florida rebuilder did not fix the issue, and the problem was ultimately resolved with a new ECM and addressing the shorted injector.

Case #4: Ford

Vehicle Information:
2008 Ford F-350 Super Duty XL 6.4L

Issue + Repair History:

• Service Engine Soon (SES) lamp was on.
• Scanned and found code P0201 for Injector Circuit.
• Verified proper resistance at injector harness and checked resistance to PCM.
• Replaced and programmed PCM, but the problem persisted.

Other OBD2 Codes + Test Results:

• P0201: Injector Circuit

Suggestions to Fix Issue:

• Consider that a mechanical problem on the injector could cause an electrical code.
• Check if the #1 fuel injector is leaking by removing the glow plug and observing if fuel comes out during cranking.
• Disconnect the ZIF connector on the PCM and check for continuity to the injector.
• Examine the 15-pin connector from the loom to the injector harness for intermittent connections due to expanded pin barrels from engine vibration.

Final Fix:

• After reassembling the truck, the same cylinder dropped during a test drive.
• Found an intermittent connection at the 15-pin connector from the loom to the injector harness due to expanded pin barrels.
• Investigating a pin extractor to repair or replace the contact as the pigtail is currently unavailable.

Case #5: Chevrolet

Vehicle Information:
2004 Chevrolet Silverado 2500 HD 6.6L

Issue + Repair History:

• ABS light intermittently on.
• Initially found codes C0550 and C0201.
• Cleaned and checked the ground connection under the driver’s cab on the frame.
• Considered EBCM reprogramming due to a reflash available for C0550.

Other OBD2 Codes + Test Results:

• C0550: EBCM Module Programming Error
• C0201: (Initially present but resolved after repairing ground connection)

Suggestions to Fix Issue:

• Check for a software update for the ABS module (EBCM).
• Wait 30 seconds with the key on before starting as a temporary workaround.
• Replace the module that set the C0550 code if it persists as current.
• Consider reflashing the EBCM before replacing it due to high costs.

Final Fix:

• The ground issue under the driver’s cab was fixed, resolving the C0201 code.
• For the C0550 code, a reflash was recommended for the ABS module.
• Awaiting final confirmation on whether the reflash resolved the issue or if a new ABS module is needed.

Advice	Diagnostic Step Description
Check Wiring and Connectors	Inspect wiring harness and connectors to the injector for signs of damage, corrosion, or loose connections.
Test Injector Resistance	Measure the resistance of the injector and compare it with the specifications and other injectors.
Swap Injectors	Swap the problem injector with another cylinder’s injector to see if the issue follows, indicating a faulty injector.
Inspect for Mechanical Issues	Check for any mechanical issues that could be causing the injector to malfunction, such as cam lobes wear.
Check for Shorts and Grounds	Look for shorts in the wiring or issues with ground connections that might be affecting injector operation.
Verify Injector Harness	Inspect the injector harness under the valve cover for damage or poor connections.
Perform a Load Test	Conduct a load test on individual wires to ensure they can handle current without voltage drops.
Replace Injector if Necessary	Consider replacing the injector if tests indicate it is faulty.
Check for ECM Software Updates	Verify if there’s an available software update or reflash for the ECM that might resolve the issue.