P0418: AIR System Control A Circuit
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Yes.
Symptoms
- Check engine light
- Pump not running or running at wrong times
- Emissions failure
Likely causes, most common first
- Pump relay control circuit fault
- Relay failed
- Wiring between computer and relay
- Pump seized and dragging the circuit down
Read P0418 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0418 points at the control side of the secondary air pump relay - the low-current wire with which the computer commands the high-current pump circuit.
One trap deserves mention: a pump that has seized from water ingestion draws enormous current, and that current can burn the relay and set control-circuit codes. Finding a failed relay and stopping there brings the car back a week later with the same complaint and a second dead relay. If the relay died, spin the pump by hand or measure its current draw before calling the repair finished.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning P0418
“Check engine light went on. Got a code p0418-vehicle will go limp/not able to go over 25mps. Toyota has a warranty repair program in place for all 2012 tundras with a 5.7 size but not mine because it is a 4.6 even though it is the exact same problem!!! *tr”2012 Toyota Tundra · Jun 2020 · 87,130 mi
“Air injection pump and air switching valve assembly. Vehicle generated an obd code of p0418 and p2441. Vehicle only has 66k miles. Vehicle is unable to accelerate to normal driving speeds, very sluggish. Cost to repair is $2k. This is the same problem on 2012 toyota tacoma and experienced on 2013 - 2015 being reported. This is dangerous to drive!”2014 Toyota Tacoma · Jan 2019 · 66,000 mi
“Service engine light came on while driving under 30mph. Engine no longer starts correctly. Only 51,000 miles. Air pump assembly and air switching valves error code. (p0418) known defunct parts for 2007 tundras which toyota extended warranty to 10 years or 150,000 miles. Warranty not sufficient length for this model year for low mileage vehicles. Could not have had properly fixed until check engine light comes on. However, parts fail at 50k+ miles. Please extend warranty to appropriate length for this issue. Numerous similar instances noted upon internet research.”2007 Toyota Tundra · Oct 2018 · 51,000 mi
Show 5 more owner reports
“I have an 2006 lexus gx470 and these lights came on: ABS, vsc trac, vsc off, skid, and check engine. The vehicle started making a humming noise at start up and now drives in stalled mode. Had codes check and it turns out I have the dreaded secondary air injection system (emissions) defect p0412, p0418 ,p1440/p1443, p1441/p1444, p2440, p2445, p1442/p1145 , which is a recurring problem. Replacement is a nightmare for self repair or a $2000+ repair.”2006 Lexus GX470 · Jun 2018 · 125,000 mi
“Code p0418 secondary air injector code keeps coming on - and is a known problem. 2011 tundras were recalled for this - so should 2012 tundras”2012 Toyota Tundra · Jun 2018 · 90,000 mi
“Check engine light came on.the code shoes p0418 air injection valve/pump. 76,000 mi on engine. Cruising down interstate lost power. Toyota extended warranty up to 2011 models.known problem”2012 Toyota Tundra · Apr 2012 · 76,930 mi
“Code p1410 secondary air injection system switching valve stuck open. This is a common error many 2006 and up subaru impreza wrx owners are having. The emissions system is prone to fail due to carbon buildup or moisture and rust contaminating valves, leading to repairs costing $700 to $1500. This failure is common even with low mileage. Note these codes are also associated with this failure: 06/07 wrx: p0410 p0411 p0413 p0414 p0416 p0417 p0418 p2431 p2432 p2433 p2440 p2441 p2442 p2443 p2444 07 sti: p0410 p0411 p0413 p0414 p0418 p2431 p2432 p2433 p2441 p2444 *tr”2006 Subaru WRX · Jan 2012 · 66,870 mi
“Code p1410 secondary air injection system switching valve stuck open. This is a common error many 2006 and up subaru impreza wrx owners are having. The emissions system is prone to fail due to carbon buildup or moisture and rust contaminating valves, leading to repairs costing $700 to $1500. This failure is common even with low mileage. Note these codes are also associated with this failure: 06/07 wrx: p0410 p0411 p0413 p0414 p0416 p0417 p0418 p2431 p2432 p2433 p2440 p2441 p2442 p2443 p2444 07 sti: p0410 p0411 p0413 p0414 p0418 p2431 p2432 p2433 p2441 p2444. *tr”2006 Subaru Impreza · Apr 2011 · 60,000 mi
Cars that report P0418 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0418?
Yes.
How much does it cost to fix P0418?
Typical US repair costs range from $20 for the simplest fix (relay) to $800 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to P0418. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.