I have a 1995 jaguar vanden plas that recently got a check engine light. I obdII scanned it and got a p0411 code. I have very limited knowledge about cars and need some help. Where do i start in narrowing down what could be causing the error? Any clue as to what the problem/how to fix this is? Thanks!

 

Your have a problem with the air injection system. No need to worry too much....not a reliability concern.

Most likely your electric air injection pump has failed. If so, you can get a rebuilt for about $100 or a new one for about $180. It's the same part used on some mid-90s Camaros/Firebirds. It is not labor intensive to replace.

First though, check the fuse for the system.

There are other possible faults. A shop with Jaguar manuals should be able to check the system.

Cheers
DD

 

I should add that my air pump is working or atleast isnt completly dead as on start up i can hear the high pitched sound coming from it. is there a way to test to see how effective the air pump is being?

After taking the outlet tube off and putting my hand to it, it is deffently blowing a decent amount of air out of it. also the fuses are good. Whats next for diagnosising it?

 

In that case, the next step would be to clear the code and see if it comes back.

 

A couple years ago I had a P0411. Fuse blown. Air pump seized. I pulled the plug, cleared the code, and forgot about the issue for a few months.

What's interesting is that the code (nor CEL) ever came on during the entire period that the pump was unplugged

<shrug>


Cheers
DD

 

I got two of 'em today...cleared 'em from the phone. Might get one or two a week, sometimes go a month or more without one. No effect on driveability - only an issue if you have an intrusive state inspection.

 

I just dealt with the CEL P0411, last week tighten an exhaust leak and when the ambient temperature got to about 65F the car would not run proper, stall and throw "black smoke" out the pipe, and one of the codes was P0411. Yesterday disconnected and plugged the EGR system and disconnected air pump. I have driven 60 miles and no codes. I have recently changed all plugs with Platinum Fours, all new coils and installed XJRengineers bracket.
The car appears to be running very smooth and very responsive, has 170,000km/105,633 mi on the odometer. Still running the code reader as the codes do not throw a light on.

B3
1995 XJR

 

well after all that the CEL turned off today by its self. Thanks for the advice tho!

 

the code came back today. it seemed to me that once it reached normal running temp. the check engine light came on. i cleared the code and hopeing it wont come back but does this narrow down what part could be causeing the fault? thanks

 

A useful place to start for understanding CEL codes is OBD-II Trouble Codes - DTC Codes Car Repair. They say this about the p0411 code:
Secondary Air Injection System Incorrect Flow Detected
What does that mean?
Secondary Air Injection is an emission control that uses an air pump (either electric or turned by the drive belt) to move fresh air into the exhaust manifold(s) or exhaust ports when the engine is in open loop and pre-catalytic converter when in closed loop. This reduces hydrocarbon emissions (HC), Carbon Monoxide (CO), and oxides of Nitrogen (NOx). This fresh air helps convert Carbon Monoxide (CO) into Carbon Dioxide (CO2) and Hydrocarbons (HC) into water vapor (H20).

A check valve is located in the air supply line to keep exhaust gasses from flowing into the pump. A cutoff valve that controls the airflow may be vacuum controlled or electrically controlled. When the powertrain control module (PCM) activates the valve, vacuum travels to the cutoff valve to open it and allow fresh air to flow. Some systems may have only a check valve and the flow may be regulated by a electromagnetic clutch on the air pump (similar to an A/C clutch).

Under hard acceleration, the air pump will be deactivated to prevent backfiring in the exhaust. To self-check, the AIR system will be activated by the PCM and fresh air would be routed into the exhaust system. The oxygen sensors would sense this fresh air as a lean condition and the short term fuel trims would begin to move in the positive direction to compensate. The PCM expects to see this happen within just a few seconds during the self test. If it does not see the short term fuel trims rise, then the PCM interprets this as a malfunction in the AIR system and a code will be recorded.

Symptoms of a P0411 DTC may include:

MIL (Malfunction Indicator Lamp) illumination
Backfiring in the exhaust under hard acceleration
Engine running rich (This is counter-intuitive. See explanation below)
Squealing belt

Potential causes of a P0411 code include:

Damaged or missing check valve
AIR pump intake port plugged/damaged
AIR pump clutch malfunction
Holes or damage to exhaust components

Possible solutions:

If you have access to a scan tool, with KOEO (Key on engine off) command the AIR pump on. It should activate. If it doesn't, remove and inspect the AIR pump relay for discoloration/melting due to heat. Repair as necessary.

With the ignition on (engine off) check for battery voltage at the switched battery feed to the relay and the relay control circuit. If either of these isn't present, inspect circuit for blown fuse or open/short in the wiring. Repair cause of short and retest. If they are both present, jumper the battery feed to AIR pump feed circuit using a fused jumper. The pump should activate. If not, check for power and ground present at the AIR pump when jumpered. If there is no voltage/ground present at pump repair open in wiring harness. If voltage and ground is present, but pump still does not run, suspect a bad AIR pump. If after jumpering the AIR pump feed circuit the pump activates then the problem is likely the AIR pump relay. Replace and retest.

If the scan tool activates the AIR pump, with KOER (Key on engine running) activate the AIR pump solenoid valve on and see if there is vacuum to the cutoff valve. It should have vacuum present to open the valve. If there is no vacuum present, check the AIR pump's vacuum solenoid valve for vacuum supply from the manifold. If there is vacuum present then the vacuum solenoid is likely bad. Replace it. If there is no vacuum present at the supply to the vacuum solenoid, check for a plugged or damaged vacuum line or plugged vacuum port. But if there is vacuum present at the cut-off valve, shut the engine off and using a vacuum pump, apply vacuum to the cut-off valve and see if it holds a vacuum and that air flows through it when vacuum is applied. If it doesn't hold vacuum or the valve doesn't flow when vacuum is applied, replace the cut-off valve. If the cut-off valve works properly, inspect the check valve for obstruction or to see if it's missing. Replace as necessary.

Check the steel line to the exhaust catalyst as well as the exhaust ports for damage or holes that could give a false reading.

 

ok

 

can a secondary air pump of xj vdp be test with 12 volts?