P0353 Code: Ignition Coil C Primary/Secondary Circuit
The circuit for coil C, which fires cylinder 3, failed its electrical check. Wiring is a big suspect.
At a glance
Severity: Moderate
- Meaning
- Ignition Coil C Primary/Secondary Circuit
- System
- Ignition & Misfire · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $80–$1,500
- DIY difficulty
- Moderate
The engine computer monitors each coil output as it fires it. P0353 means the third output, coil C, did not produce the current rise or feedback signal the computer expects, so the problem is electrical: the coil, its connector, its feed and ground, or the trigger wire. On three-cylinder engines such as Ford's 1.0L EcoBoost or Mitsubishi's 1.2L, coil C is the last coil, at the transmission end. On transverse V6s it often sits on the rear bank against the firewall, and on Toyota and GM V6s cylinder 3 is the middle of that rear bank, under the intake plenum. Because coil C's wiring is often buried there, chafed or chewed wires are a bigger share of P0353 faults than on the easy-to-reach coils.
Can I keep driving? You can usually drive gently to a shop, but the engine is down a cylinder. If the car will sit outdoors for days, fix the cause soon: rodents that chewed one wire often come back for more.
How to read P0353
- P Powertrain
- 0 Generic (SAE)
- 3 Ignition / misfire
- 53 Specific fault
Symptoms
- Rough idle with a steady, rhythmic miss
- Check-engine light on, typically with P0303
- Miss comes and goes over bumps or when the engine rocks on its mounts
- Nesting material, droppings or chewed insulation under the engine cover
- Reduced power, especially on three-cylinder engines where one dead cylinder is a third of the engine
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Coil C has failed internally
- Coil C wiring chewed by rodents or chafed through against a bracket or the plenum
- Coil C connector loose, corroded or with a broken latch
- Voltage drop on the coil feed or ground from a corroded splice or ground eyelet
- Moisture in the cylinder 3 plug well causing the boot to track to ground
- Low-quality replacement coil from an earlier repair that doesn't match the original's electronics
- Coil C driver inside the engine computer has failed
Diagnosis step by step
Find cylinder 3 and plan the access
On an inline three it is the last cylinder at the transmission end, and on an inline four it is third from the timing end. On transverse Toyota and GM V6s it is the middle of the rear bank under the plenum, and on transverse Ford and Honda V6s it is the rear bank at the transmission end. On a GM V8 it is second from the front on the driver side, and on a Ford V8 third from the front on the passenger side.
Tools: Flashlight
Look for animal damage and chafing
Lift the engine cover and look along the coil harness for droppings, nest material, gnawed insulation and bare copper. Also check where the harness rubs on the plenum or a bracket. A single bitten trigger wire is enough to set P0353.
Tools: Flashlight
Voltage-drop test the feed and ground
With the engine running, back-probe the coil C feed pin and measure to the battery positive post: more than about 0.5 volt means resistance in the feed. Then measure from the coil ground pin to the battery negative post: more than about 0.2 volt means a bad ground. These tests under load find corroded splices a simple voltage check misses.
Tools: Multimeter
Wiggle test with live data
With the engine idling and the scan tool showing the cylinder 3 misfire counter, gently flex each section of the coil C harness and its connector. A jump in the counter or a stumble while you move one spot shows you exactly where the break is.
Tools: OBD-II scanner
Swap coil C with another coil
Swap coil C with coil 1, or with a neighbor on the same bank if the plenum is already off. If the code follows the coil, replace it with an original-equipment quality part. If it stays on cylinder 3, keep working on the wiring.
Tools: Screwdriver, OBD-II scanner
Repair the wiring properly
Join damaged wires with solder and heat shrink, or sealed crimp connectors, never twist and tape. Cover the repair with split loom tubing and secure it away from sharp edges. If rodents were the cause, clean out the nest material, because the smell draws them back.
Tools: Pliers, Multimeter
Where the parts are
- 1Ignition coil
- 2Spark plug
- 3Fuel injector
- 4Camshaft sensor
- 5Crankshaft sensor
- 6Engine computer (ECM)
- 7Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Replace coil C (easy access) | Yes | $80–$250 |
| Replace coil C on a rear bank under the plenum | No | $250–$600 |
| Repair rodent-damaged or chafed coil wiring | No | $100–$400 |
| Clean and repair coil ground or feed splice | No | $80–$250 |
| Replace engine computer (rare) | No | $600–$1,500 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Field data
| Ford | 3 | Escape Hybrid, Edge |
|---|
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.
Emissions / smog test impact
Will fail
P0353 turns on the check-engine light and fails an OBD-II smog or emissions inspection. On a three-cylinder engine the misfire is also strong enough to push tailpipe readings up at stations that still sniff the exhaust.
Frequently asked questions
My car has a three-cylinder engine. Is coil C the last one?
Yes. On three-cylinder engines coil C fires cylinder 3, which sits at the transmission end of the engine. Losing it costs a third of the engine's power, so the misfire is very noticeable.
Do I have to remove the intake to reach coil C?
On many transverse V6s, yes. On Toyota and GM V6s cylinder 3 is on the rear bank under the plenum, so the upper intake comes off. That labor is the reason many owners replace all the rear-bank coils and plugs in one visit.
Can animals really cause P0353?
They can. Mice, rats and squirrels nest in warm engine bays and chew wire insulation. One bitten trigger or feed wire is enough to set a coil circuit code, and it often shows up after the car has been parked for a while.
Will insurance pay for chewed wiring?
Comprehensive coverage often includes animal damage, but policies differ. Take photos of the damage and any nest material before the repair, and ask the shop to note the cause on the invoice.