P0350 The computer found a fault in the primary or secondary circuit of an ignition coil

Ignition coil primary/secondary circuit malfunction

Severity not verified — if the car runs badly, have it inspected

The sources read for this code define it and list causes but do not rate how urgent it is. A coil circuit fault can cause a misfire, so have it checked rather than ignoring it.

Source: how we rate severity

P0350 in short

P0350 means the engine computer found a fault in the primary or secondary circuit of an ignition coil. A failed coil, damaged wiring or a loose connector is the usual cause, and the computer itself is rare. Expect a check engine light and possibly a misfire.

Each ignition coil turns battery voltage into the high voltage that fires a spark plug. The computer watches the coil circuit, and P0350 sets when a single coil circuit (no letter) does not behave as expected.

TroubleCodes.net lists three causes: a faulty coil, wiring or connector trouble in the coil circuit, and, less often, the engine computer. It notes the code often appears with misfire codes P0300 to P0308.

The Delaware DMV list gives the same generic title, so the meaning is the same on every make. Which cylinder the letter points to depends on the engine, so check service information for your vehicle.

Most likely causes

These are general causes for this code across vehicles. None is specific to one make or model.

  1. Failed ignition coil

    Common general cause
    Why it ranks here
    TroubleCodes.net lists a faulty coil first among causes of this code.
    What would change this
    Rises if the fault follows the coil when swapped or its resistance is out of range. Falls if it stays with the same cylinder.
    How to test the ignition coil

  2. Damaged wiring or loose connector at the coil

    Common general cause
    Why it ranks here
    TroubleCodes.net lists wiring problems in the coil circuit as the second cause.
    What would change this
    Rises if the connector is corroded, loose or the wiring is damaged. Falls if the wiring tests fine.

  3. Engine computer (PCM) fault

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net lists the computer last and says it is the least likely cause, so rule out the coil and wiring first.
    What would change this
    Rises only after the coil, power and wiring all test good. Falls if any of those is faulty.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all stored codes and freeze-frame data, and note whether misfire codes such as P0300 to P0308 are stored with P0350.

    Low riskTool: OBD-II scan tool

    • IfMisfire codes are stored too

      It meansThe coil circuit fault is probably causing the misfire.

      Go to step 2

    • IfOnly P0350 is stored

      It meansInspect the coil and connector.

      Go to step 2

  2. With the engine off and cool, look at the coil and its connector for broken wires, corrosion or damage, then swap the coil with one from another cylinder and clear the codes.

    Use cautionTool: basic hand tools, scan tool

    Warning:Never touch coils, plug wires or connectors while the engine is running or cranking; ignition voltage can shock you. Let the engine cool before touching parts near the exhaust.

  3. Measure coil resistance (primary about 0.4 to 2 ohms, secondary about 6,000 to 15,000 ohms, per TroubleCodes.net; confirm against your service specs), check for about 12 volts at the coil, and use an LED or noid light to see whether the computer switches the coil while cranking.

    Best left to a shopTool: multimeter, noid light or LED test light

    Warning:Probing coil connectors with the circuit live can short a pin and damage the computer or coil driver, and ignition voltage can shock you. Leave this to a shop unless you have the wiring diagram.

Symptoms

  • Check engine light on
  • Engine misfire, rough running
  • Misfire codes P0300 to P0308 stored with it

Compare with: Rough idle with the check engine light on

How to fix

Parts and cost context

  • Ignition coil:Swap the coil with another cylinder first so you replace the right one. Labor varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Ford

  • 2003–2004 · Thunderbird

    Supported by vehicle data

    Ford bulletin 17382 covers DTCs P0300 to P0308 or P0350 to P0358. Whether it is still current is not verified.

  • 2000 · Crown Victoria

    Supported by vehicle data

    Ford bulletin 0116 covers the check engine light, rough idle and DTCs P0350 to P0360 stored in memory; Ford bulletin 8077 covers coil DTCs P0350 through P0358, the check engine light and a rough idle under cold-start conditions; Ford bulletin 8190 covers coil DTCs P0350 to P0358, the check engine light and a rough idle. Whether it is still current is not verified.

  • 1999–2000 · E-Series

    Supported by vehicle data

    Ford bulletin 0116 covers the check engine light, rough idle and DTCs P0350 to P0360 stored in memory; Ford bulletin 8077 covers coil DTCs P0350 through P0358, the check engine light and a rough idle under cold-start conditions; Ford bulletin 8190 covers coil DTCs P0350 to P0358, the check engine light and a rough idle; Ford bulletin 6902 covers 4.6L engines showing the check engine light and DTCs P0350 to P0354 for the coil system; Ford bulletin 9913121 covers engineering investigating 4.6L vehicles that show the check engine light and DTCs P0350 to P0354. Whether it is still current is not verified.

  • 2000 · Excursion

    Supported by vehicle data

    Ford bulletin 0116 covers the check engine light, rough idle and DTCs P0350 to P0360 stored in memory. Whether it is still current is not verified.

  • 2000 · Expedition

    Supported by vehicle data

    Ford bulletin 0116 covers the check engine light, rough idle and DTCs P0350 to P0360 stored in memory; Ford bulletin 8077 covers coil DTCs P0350 through P0358, the check engine light and a rough idle under cold-start conditions; Ford bulletin 8190 covers coil DTCs P0350 to P0358, the check engine light and a rough idle. Whether it is still current is not verified.

  • 2000 · F-150

    Supported by vehicle data

    Ford bulletin 0116 covers the check engine light, rough idle and DTCs P0350 to P0360 stored in memory; Ford bulletin 8077 covers coil DTCs P0350 through P0358, the check engine light and a rough idle under cold-start conditions; Ford bulletin 8190 covers coil DTCs P0350 to P0358, the check engine light and a rough idle. Whether it is still current is not verified.

  • 17382Status unverified

    DTC P0300-P0308 or P0350-P0358

    2003–2004thunderbird · issued · NHTSA 10008194

    Bulletin titled for diagnostic trouble codes P0300 to P0308 or P0350 to P0358. Only the NHTSA summary was read, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 0116Status unverified

    MIL, rough idle and DTCs P0350-P0360 stored

    2000crown-victoria, econoline, excursion, expedition, f-150, f-super-duty · issued · NHTSA 618072

    Bulletin on some vehicles that may show the check engine light, rough idle and DTCs P0350 to P0360 stored in memory. Only the NHTSA summary was read, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 8077Status unverified

    Coil DTCs P0350-P0358, check engine light, rough cold-start idle

    2000crown-victoria, econoline, expedition, f-150, super-duty-f-series · issued · NHTSA 612278

    Bulletin on some vehicles that may show any of the coil DTCs P0350 through P0358, with the check engine light on and a rough idle under cold-start conditions. Only the NHTSA summary was read, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 8190Status unverified

    Coil DTCs P0350-P0358, check engine light, rough idle

    2000crown-victoria, econoline, expedition, f-150, super-duty-f-series · issued · NHTSA 612342

    Bulletin on some vehicles that may show any of the coil DTCs P0350 to P0358, with the check engine light on and a rough idle. Only the NHTSA summary was read, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 6902Status unverified

    4.6L engines, MIL and coil system DTCs P0350-P0354

    1999econoline · issued · NHTSA 6090208

    Bulletin on vehicles with 4.6L engines that may show the check engine light and DTCs P0350 to P0354 for the coil system. Only the NHTSA summary was read, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 9913121Status unverified

    Engineering investigating 4.6L MIL and DTCs P0350-P0354

    1999econoline · issued · NHTSA 609043

    Bulletin saying engineering is investigating conditions on 4.6L vehicles that show the check engine light and DTCs P0350 to P0354. Only the NHTSA summary was read, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0351Ignition coil A primary or secondary circuit fault

    Same system Common general cause

    Both are ignition coil primary/secondary circuit codes for different coils.

All Ignition and engine position sensors codes

Sources and review

  1. P0350 trouble code page — TroubleCodes.net
  2. 17382: DTC P0300-P0308 or P0350-P0358 — Ford
  3. 0116: MIL, rough idle and DTCs P0350-P0360 stored — Ford
  4. 8077: Coil DTCs P0350-P0358, check engine light, rough cold-start idle — Ford
  5. 8190: Coil DTCs P0350-P0358, check engine light, rough idle — Ford
  6. 6902: 4.6L engines, MIL and coil system DTCs P0350-P0354 — Ford
  7. 9913121: Engineering investigating 4.6L MIL and DTCs P0350-P0354 — Ford
  8. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
Last reviewed
Written by
Saurabh K.
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