P0357 The computer found a fault in the primary or secondary circuit of ignition coil G (cylinder 7 by the usual reading)

Ignition Coil G 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

P0357 in short

P0357 means the engine computer found a fault in the primary or secondary circuit of ignition coil G, which the page reads as cylinder 7 (lettering depends on the engine). 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 P0357 sets when coil G 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 P0357.

    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 P0357 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

  • 1997–1999 · E-Series

    Supported by vehicle data

    NHTSA flat-file summary of Ford bulletin 12744 (summary: some vehicles may show a lit MIL with P0351 and/or P0357, described as a coil primary circuit malfunction). Whether it is still current is not verified.

  • 12744Status unverified

    MIL with P0351 and/or P0357

    1997–1999e-series, f-series · issued · NHTSA 607071

    NHTSA flat-file summary only; the full bulletin was not read. The summary mentions some vehicles may show a lit MIL with P0351 and/or P0357, described as a coil primary circuit malfunction.

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

  • P0356Ignition coil F primary or secondary circuit fault (the coil for cylinder 6 on most engines)

    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. P0357 trouble code page — TroubleCodes.net
  2. 12744: MIL with P0351 and/or P0357 — Ford
  3. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
Last reviewed
Written by
Saurabh K.
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Used once to identify your engine; not stored.