What P0390 means
Camshaft position sensor B is the exhaust camshaft sensor; bank 2 is the side without cylinder 1, so the code only occurs on V and boxer engines with one exhaust cam sensor per bank.
How the engine computer detects it
P0390 means no or too few exhaust cam pulses arrive from bank 2 while the crankshaft turns. GM's 3.0 twin-turbo V6 (LGW) sets it after 5.5 s without a cam pulse, 4 s of cranking or fewer than 4 pulses in 3 s, after two trips; for GM it collects all circuit faults. GM's 3.6-liter V6 in the Saab 9-4X also counts 800 of 1,000 engine cycles without a pulse. Ford checks the crank-to-cam ratio from 200 rpm within 5 s, and the 2004 Northstar counts missing signal changes up to 16. The bank 2 exhaust phaser then locks in its base position; the engine keeps running on the crank and intake cam sensors. FCA advises saving the synchronization data before replacing the sensor.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on
- Loss of power (bank 2 exhaust cam timing in its base position)
- Longer cranking
- Rough idle
- Higher fuel consumption
Common causes
- Connector or wiring of the bank 2 exhaust sensor open or corroded (signal, 5 V, ground) Most likely
- Camshaft position sensor faulty Most likely
- Oil contamination or leak at the sensor, sensor loose Possible
- Tone wheel on the phaser damaged or wrongly fitted after timing chain work Possible
- Engine module, or 5 V reference shorted by another sensor Less likely
How to diagnose P0390
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: camshaft position sensor exhaust, camshaft tone wheel, sensor wiring, engine control module, cam phaser exhaust bank2.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report P0390 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Ford F-150 | 2013–2020 | 3 | — |
Counts of owner complaints to the NHTSA that mention P0390 (4 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 3
- Ignition system or misfire
- 90
- Specific fault
Questions drivers ask
Can I drive with code P0390?
Drive gently and only as far as you need to. The engine computer may limit power to protect the engine, so avoid highways and heavy traffic until it's fixed. If the check engine light starts flashing, pull over.
Will my car pass an emissions inspection with P0390?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P0390 clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
Can I fix P0390 myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: medium. Start with the cheapest checks before replacing expensive parts.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.