Overboosting 2.2 Diesel I-Ctdi - Solutions?

[James-jtec]

Hi folk,

I’m the owner of a Honda Accord 2.2 I-Ctdi diesel. It’s a fabulous car to drive.
Bought it May 2025, 1 owner, at 110k miles.
Fast forward to April 2026, it’s at 125k miles. I’m hoping in time to make it to 200k miles.

What regular maintenance tips would you recommend? How regular would you recommend a full service? I do have spare money, not super tight on budget.

I’m doing easily 90 miles a day for work round trip.

After a recent private diagnostic through a friend, I’ve had the following error codes:


After an OBD2 tool scan, the error codes appear:

P1236 - Boost pressure higher than expected
U0122 - F-CAN malfunction (ECM)-VSA modulator control
P16A4 - Enginr control module (ECM) internal control malfunction

ABS-VSA
17-1 left rear wheel speed sensor open or short
18-1 left rear wheel speed sensor failure
19-1 left rear pulsar failure
61-1 battery voltage failure
B1325 - Rain sensor infrared rays error (RSM Message)


Please can you advise what I should say to my local garage with regards to these error codes?

Thanks

 

[F6HAD]

Are these active or historic error codes? Is the engine light on and is the car in limp mode? If not then I would wipe them all and check again after a week of driving to see what returns.

Maintenance wise:

Every 7-10k miles depending on driving profile, give it an oil and filter change with 0w30 fully synthetic.
Every second service I would also renew air and pollen filters
Every third service I would do the fuel filter

Other stuff like coolant, brake fluid, gearbox oil I would do now if there’s no history of it having been done and really if you hit the 200k mile marker I would do them again then.

Some of these engine codes might relate to the car having a bad remap, but as I said clear them off first and see if any return.

 

[Troy McClure]

If the overboost is real, there's a grub screw to limit the turbo wastegate. On an i-DTEC it's under the heat shield which means removing the lambda sessor, not sure about the i-CDTi, but it might need adjustment. (If it's a historic code, maybe the previous owner tried to squeeze a bit more power out of it without knowing what they were doing.)

 

[Channel Hopper]

Brake calipers, check the disc/pads are not overheating (rear left especially)
Earthing points and corrosion under the bonnet. Don't park/live near the coast.
If a saloon make sure you have a way of getting into the boot.
Get a spare key and always keep a replacement battery for it in the car. (Important if somebody tries forcing the driver door lock)
Keep things as standard as is possibe for a long life.

 

[James-jtec]

Thank you both for replying with details.

So these error messages appeared on my car last Friday. There was in fact an engine light, this was reset. I’ve had a week of driving 80-90 miles a day minimum on A roads.

The engine light first appeared when I had accelerated, pedal to metal, in 4th gear, I was on an A-road 60mph on an incline road suddenly went to 40mph limp mode. That’s when the engine light first appeared as I was commuting to work on a Monday morning.

Pulled over, turned off the ignition, turned back on, car was out of limp mode and started driving as usual but with the engine light. I had been cautious since that moment.

My car is a mk7 using the i-Ctdi 2.2 diesel engine. In the last week over 150 miles it’s been averaging around 48.8mpg on an A-Road. However, it was driving 32-25mpg a couple days after the engine light appeared then I decided to drive 10 mins in 3000 rpm (3rd gear) as I heard this may clear the soot? After that the mpg had improved.

When I was sold the car the question of a remap didn’t come to mind, I have no reason to believe a remap has happened. But perhaps a professional might be able to verify this.


The car is actually going into a garage for a full-service tomorrow morning. Any questions I could ask the garage related to these error codes?

I have been thinking of getting a carbon clean with this car. Is that a good idea?

I’m willing to give any services that might benefit its longevity. Such as spraying the underbody with a protective spray?

Thanks again for all the replies. Will report to the garage and see what they recommend tomorrow.

 

[F6HAD]

It needs an engine tuner to inspect the ecu flash to understand if it’s remapped. It’s something I could do if you want to get in touch. Now that you’ve explained that this is a current problem I would say it’s possibly a bad remap and/or a sticking turbo.