The OBD2 code P0320 indicates an issue with the ignition/distributor engine speed input circuit, signaling problems in the system responsible for monitoring the engine’s RPM. When this circuit malfunctions, it can lead to engine stalling, difficulty starting, or a complete failure to start, as evidenced by the service cases involving vehicles from Jeep, Ford, and Mazda.
P0320 quick overview
| Meaning | P0320: Ignition/Distributor Engine Speed Input Circuit Malfunction |
| Is it serious? | Yes, it can result in engine stalling, starting problems, and potentially leave you stranded. |
| Possible causes | – Faulty crankshaft position sensor – Damaged camshaft position sensor – Wiring or connector issues related to these sensors – Potential PCM problems – Electromagnetic interference affecting sensor signals |
| How to diagnose? | Inspect the crankshaft position sensor for damage or malfunction Check the camshaft position sensor and its synchronization Verify wiring integrity from the sensors to the PCM Scope both sensors to ensure accurate signal generation Investigate for electromagnetic interference that could disrupt sensor operation Consider PCM issues, especially if cooling it temporarily solves the problem |
P0320 Meaning
Imagine your vehicle’s engine as a complex dance of mechanical parts, with the crankshaft and camshaft position sensors acting like conductors, ensuring everything moves in harmony. The P0320 code means there’s a glitch in this orchestration, with the engine’s control unit missing crucial cues about its speed.
This miscommunication can cause your engine to stall or struggle to start, akin to a conductor losing the beat in a musical performance. Addressing this issue often involves checking these sensors and their connections to keep the engine’s rhythm smooth and uninterrupted.
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How to fix P0320 – learn from mechanics
I looked into P0320 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: Jeep
Vehicle Information 1999 Jeep Cherokee Limited 4.0L
Issue + Repair History
- Vehicle stalls immediately after starting.
- Code P0320 detected.
- Fuel pressure at 40 psi.
Other OBD2 Codes + Test Results
- P0320
Mechanic Suggestions
- Verify wiring integrity.
- Inspect crankshaft position sensor for failure.
- Check camshaft position sensor.
- Scope both sensors for accurate diagnosis.
- Replace crankshaft position sensor with OEM part.
- Consider replacing camshaft position sensor.
- Ensure proper setting/verification of cam sensor sync.
- Investigate possibility of cracked flexplate affecting crank sensor signal.
Final Fix
- Replaced crankshaft position sensor with OEM part and verified cam sensor sync, resolving the issue and preventing stalling.
Case #2: Ford
Vehicle Information 1997 Ford E-350 Econoline 6.8L
Issue + Repair History
- Recurring code P0320 for three years.
- Intermittent issue, takes up to a couple of months for the light to come back on.
- Crank sensor replaced at least twice.
- Driveshaft retarder disconnected to eliminate interference.
- No two-way radio installed.
- Coil-on-plug vehicle.
- Customer states vehicle runs smoothly, no misfires or stalling.
- Plugs are new.
Other OBD2 Codes + Test Results
- P0320
Mechanic Suggestions
- Check secondary ignition components (plugs, wires, etc.).
- Verify all 2-way radio installations and follow manufacturer’s instructions regarding routing of antenna and power leads.
- Inspect for loose connection in the crank sensor plug.
- Investigate electromagnetic interference, potentially caused by alternator or faulty coil.
- Stress test each coil to identify any potential issues.
- Access Mode 6 data in PCM OBD2 monitors to pinpoint misfire data and identify problematic coil.
- Examine shielding on wiring from crank sensor to PCM for corrosion, consider rewiring and reshielding if necessary.
Final Fix
- Bypass existing crank sensor wiring and fabricate a shielded wire to the PCM.
Case #3: Mazda
Vehicle Information 1997 Mazda B4000 SE 4.0L
Issue + Repair History
- Truck stalled (engine went dead) multiple times, engine would turn over but not restart immediately.
- MIL came on after the second stall.
- Only one code retrieved: P0320.
- No injector pulse observed during diagnostics.
- Canned air on PCM temporarily resolved the issue.
- Wiring plug at PCM checked.
- Sent PCM to Texas for repair.
Other OBD2 Codes + Test Results
- P0320
Mechanic Suggestions
- Replace PCM or send it in for repair due to P0320 code indicating PCM malfunction.
- Check with remanufacturers for PCM availability.
- Consider replacing PCM if keeping it cool allows the engine to stay running.
Final Fix
- Sent PCM to Texas for repair as suggested. The invoice recommended checking grounds, which were found to be good upon installation and inspection. Truck has been out for 10 days with no problems, marking the issue as fixed.
How to diagnose P0320
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Diagnostic Step | Explanation |
|---|---|
| Inspect crankshaft position sensor | Check for physical damage or signs of failure. |
| Check camshaft position sensor | Ensure it’s properly synchronized and functioning. |
| Verify wiring integrity | Look for damaged wires or loose connections affecting signals. |
| Scope both sensors | Use an oscilloscope to confirm accurate signal output. |
| Investigate electromagnetic interference | Check for sources of interference that could affect sensor signals. |
| Consider PCM issues | If temporary cooling of the PCM helps, a deeper inspection or replacement may be needed. |
Resolving a P0320 code involves a thorough inspection and possibly replacing sensors or rewiring to ensure the engine receives accurate speed signals. Given the technical nature of these diagnostics, professional assistance is often required to accurately identify and fix the underlying issue, ensuring reliable engine performance.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko