P2303 OBD-II Trouble Code: Ignition Coil “B” Primary Control Circuit Low

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P2303 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P2303 code

P2303 is a diagnostic trouble code (DTC) for "Ignition Coil “B” Primary Control Circuit Low". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
SCHEDULE P2303 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light

P2303 code definition

Ignition Coil “B” Primary Control Circuit Low

What the P2303 code means

P2303 is an OBD-II generic code for the engine control module (ECM) detecting a coil “B” primary control circuit low. This can be due to a short or open in the coil or in the wiring circuit to the coil's primary circuit.

What causes the P2303 code?

  • The engine control module (ECM) monitors the coil's primary control circuit and if the control circuit senses the voltage below specifications, then it will turn on the Check Engine Light and set code P2303.

  • The primary coil has internal shorted windings and causes the return voltage to go low.

  • The primary return wiring is shorted to ground or cut in the harness back to the ECM.

What are the symptoms of the P2303 code?

  • The Check Engine Light will be illuminated and the code is set in the ECM memory as a fault.

  • The engine will run very rough or not start at all depending on if the coil failure is intermittent or not.

  • The engine may run good and then all of a sudden stall or run very rough when short occurs.

How does a mechanic diagnose the P2303 code?

  • Scans for codes and documents any codes in the ECM, then looks at the freeze frame data for failure

  • Checks the coil for carbon tracking, cracks, or wiring harness cut into causing the short

  • Removes the coil connection and tests the coil for shorted primary windings

  • Checks the wiring harness for shorts or open circuits from coil to the ECM

Common mistakes when diagnosing the P2303 code?

  • Clearing ECM memory codes before checking the freeze frame data for the main failure problem, so the failure may be duplicated and repaired.

  • Replacing the coil when the harness has a short in the wiring and not doing a full diagnostic pinpoint check before replacing parts.

How serious is the P2303 code?

Code P2303 is a code indicating the coil's primary circuit has failed and most likely will result in a no start or stall of the engine since this is a second coil in a two coil engine.

What repairs can fix the P2303 code?

  • Repairing or replacing the coil wiring harness or connector
  • Replacing a shorted coil and checking the ECM for coil driver problems
  • Replacing the ECM due to a burned out coil driver circuit and replacing the coil

Additional comments for consideration regarding the P2303 code

Code P2303 is most commonly caused from an internal coil primary circuit short or open windings. The failure may burn out the ECM coil driver. If the coil and ECM are not replaced at the same time, the ECM may get burned out if it is replaced without a new coil also. Always check the coil's primary resistance for problems if replacing the ECM.

Need help with a P2303 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

trouble codes
Check Engine Light
P2303

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P2303 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

3,484

Rating Summary
3,176
153
40
23
92
3,176
153
40
23
92

Richard

10 years of experience
415 reviews
Richard
10 years of experience
This is the second time I’ve had Richard work on my car. He always does an outstanding job and is quick, knowledgeable and professional. Highly recommended!!
2012 DODGE CHALLENGER - CHECK ENGINE LIGHT IS ON - LAS VEGAS, NEVADA

Michael

13 years of experience
372 reviews
Michael
13 years of experience
Mike was an absolute professional when he arrived. He walked me thru the whole process of my repairs and also made good recommendations for preventive issues. His mechanical knowledge and good customer services was a breath of air and greatly appreciated :-)
2007 CHEVROLET AVALANCHE - CHECK ENGINE LIGHT IS ON INSPECTION - MARIETTA, GEORGIA

Rodrigo

10 years of experience
85 reviews
Rodrigo
10 years of experience
Rodrigo was exactly on time, very professional and friendly. He assessed my car, let me know the exact problem when a previous mechanic from a shop in my area was unable to. I felt he was very honest and sincere letting me know the level of urgency that I deal with the issue. Absolutely no pressure. I will absolutely use Rodrigo the next time I need anything to do with my car and will tell everyone about him. This is such a great service, I will never go to another mechanic again. It is so convenient. I couldn’t be happier. :)
2013 SMART FORTWO - CHECK ENGINE LIGHT IS ON - LAS VEGAS, NEVADA

Ricardo

8 years of experience
223 reviews
Ricardo
8 years of experience
Great service and was very helpful on what maintenance my vehicle needed and what to expect in the future. Would definitely recommend to anyone and will.
2004 MITSUBISHI LANCER - CHECK ENGINE LIGHT IS ON - LOS ANGELES, CALIFORNIA

More related articles

How to Get a Louisiana Driver's Permit
s licensing program. The first step in this program is to obtain...
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...

Related questions

Q: Code P0303 cylinder 3 misfire

The symptoms you describe along with the blinking Check Engine Light and P0303 trouble code definitely tell us that you have a misfire in cylinder number 3. Your engine uses a coil on plug system. This means each individual...

Q: I have the check engine light on and checked for DTC's it says ECM set and CEM set

Hi there, thanks for writing in about your Volvo. There should be specific alpha numeric "codes" displayed on the Code Reader. Do you see/have those "codes"? These will help pinpoint any faults and assess the issue. I would recommend having...

Q: The Check Engine Light is on but the scanner shows no codes.

The brand, type, quality, and manufacturer coverage of the scanner you bought will dictate how they read the codes. Unfortunately, not all scan tools are created equal. When it comes to hybrid vehicles, you may want to make sure you...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com