In this article the problematic subject vehicle was brought to an Autologic equipped shop by a neighboring repair shop. They were fighting a reoccurring P0339 that would set once on average once per day.
A P0339 - Crankshaft Position (CKP) Sensor Circuit Intermittent Interruption sets when the Hall Effect sensor signal received by the PCM has an incorrect amount of signal pulses between reference pulses. What that means is, if there are supposed to be 58 pulses between the reference pulses, and 57 or 59 are seen, this fault code will set. The amount of pulses is determined by the number of slots in the tone ring for the sensor.
Honda General Description
The crankshaft position (CKP) sensor consists of a rotor and a semiconductor that detects rotor position. When the engine starts, the rotor turns and the magnetic flux in the semiconductor device changes. The changes of magnetic flux are converted into pulsing signals to the engine control module (ECM)/powertrain control module (PCM). The CKP sensor detects injection/ignition timing for each cylinder and engine speed. If an abnormal amount of pulsing signals from the CKP sensor are detected, the ECM/PCM detects a malfunction and stores a DTC.
The first step we instructed the technician work on the vehicle to scan the PCM and read current faults. The P0339 was current. Depending on the fault and situation, in can be counterproductive to clear a fault code before diagnosis, in this case we felt the opposite. We asked the tech to clear fault, test drive vehicle from a cold start and read faults. The tech followed up, advising us the code did not return.
We’ve confirmed the fault code and that it is intermittent. Now to duplicate the customer’s concern. The tech could not set the fault code throughout the day driving and restarting the vehicle. However, when driven home and started in the morning, the MIL was on and the P0339 was set.
Confirmed, now to test. The tech connected directly to the PCM crankshaft sensor signal at terminal C45. The tech sent over the signal file and after a quick review we noticed a sensor ground was lifting when the engine cranked. Generally a ground can have some voltage drop, but I like to see 0.2 volts DC normally with a max of 0.5 volts DC.
- In this case the camshaft sensor ground lifted about 1.2 volts DC. (red scope trace)
- Also note the spike at the top of the crankshaft sensor signal. This could be when the PCM sees the additional pulse, setting the P0339 fault code. (green scope trace)
- Battery voltage was above 10.6 the entire time and the battery passed a load test. (yellow trace)
Right away this looked like a faulty sensor / engine / battery ground. We asked the tech to add a ground at the sensor and connect it directly to battery negative. The ground lifted less than 0.5 volt with the test ground in place. We then ran a jumper cable from battery negative to the engine block, the ground lifted less than 0.2 volts.
With an inspection of the battery cable it was found to be corroded and green. The cable was replaced, then the signal rechecked and it remained under 0.5 volt DC. The tech then drove the car home for two days and the MIL did not return, problem solved.
Cable attaching point - Corroded
Keep in mind, other issues can cause this fault code:
- Faulty starter motor – too much current draw
- Weak battery or parasitic draw pulling battery down overnight
- Faulty sensor or sensor wiring
- Faulty PCM
- Use OEM crankshaft sensors when replacing
Need help diagnosing a Honda or Acura? Contact Autologic for help.