P2A59 code meaning
Alternative Fuel Vaporizer B Outlet Temperature Sensor Circuit Intermittent/Erratic
Powertrain system Generic code P2Axx codes Check engine light
What P2A59 means
On heavy vehicles the gas hardware sees constant shaking, and long harness runs to the vaporizers add connectors that can loosen. P2A59 records that the vaporizer B outlet signal changed faster or more erratically than real temperature can, or kept dropping out for short moments. Such faults tend to come and go with road surface, engine speed or coolant heat. The A sensor gives a good reference: if its value is smooth while B jumps, the problem is local to the B circuit. Look for green corrosion at the pins, cracked insulation and strain on the plug. No manufacturer documents P2A59; CARB still requires that sporadic faults on an input like this are detected. Expect occasional switching to gasoline or a flickering gas indicator.
P2A59 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P2A59
- Check engine light comes and goes, depending on calibration
- Sporadic switching to gasoline
- Flickering gas indicator
Common causes of P2A59
- Most likelyConnector of the B sensor loose or corroded
- PossibleHarness damaged by vibration or strain
- Less likelyIntermittent contact inside the sensor
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Alt fuel vaporizer b outlet temp sensorWiring harnessAfcm
What each part of P2A59 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| A | Area: hybrid propulsion. |
| 59 | The exact fault in that area. |
What to do next
- Note P2A59 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2A59
What does P2A59 mean?
P2A59 means "Alternative Fuel Vaporizer B Outlet Temperature Sensor Circuit Intermittent/Erratic". On heavy vehicles the gas hardware sees constant shaking, and long harness runs to the vaporizers add connectors that can loosen. It is a generic code, so it means the same on every make.
Is it safe to drive with P2A59?
Drive gently and only to a workshop. With P2A59 the car can go into limp mode (reduced power) to protect itself.
Will P2A59 fail an emissions test?
Yes, it can. P2A59 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2A59 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P2A59 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.